[Security Solution] When adding an Exception and Source value on the Severity override option, are not offering suggestions (#150701)

## Summary

These changes fixes the issue with the broken field source value
auto-suggestion which was caused by [this
PR](https://github.com/elastic/kibana/pull/149149/files#diff-2b9142306df119b8c31e8a66c9b93b2a83f74239b1655919881165ac06398623R148).

The problem is that the `stringifyIndices` variable is used to:
1. represent all indices down the road where we request suggestions for
a field in
`src/plugins/unified_search/public/autocomplete/providers/value_suggestion_provider.ts`
2. be a parameter to check whether we should memoize the results of
`getIndexFields` and `getDataViewStateFromIndexFields` methods

By modifying it to include the notion of whether we should include
unmapped information, solves the second point but breaks the first one.
Thus, suggestion request stopped working.

The fix is to revert changes to `stringifyIndices` variable and add
extra parameter to `getIndexFields` and
`getDataViewStateFromIndexFields` methods, so that we can take into
account `includeUnmapped` flag during memoization.

Bug ticket #150663

---------

Co-authored-by: Kibana Machine <42973632+kibanamachine@users.noreply.github.com>

x-pack/plugins/security_solution/cypress/e2e/exceptions/add_edit_flyout/flyout_validation.cy.ts

@@ -74,7 +74,7 @@ describe('Exceptions flyout', () => {
     createExceptionList(getExceptionList(), getExceptionList().list_id).then((response) =>
       createCustomRule({
         ...getNewRule(),
-        dataSource: { index: ['exceptions-*'], type: 'indexPatterns' },
+        dataSource: { index: ['auditbeat-*', 'exceptions-*'], type: 'indexPatterns' },
         exceptionLists: [
           {
             id: response.body.id,
@@ -289,11 +289,28 @@ describe('Exceptions flyout', () => {
     openExceptionFlyoutFromEmptyViewerPrompt();
 
     cy.get(FIELD_INPUT).eq(0).click({ force: true });
+    cy.get(FIELD_INPUT).eq(0).type('unique');
     cy.get(EXCEPTION_FIELD_LIST).contains('unique_value.test');
 
     closeExceptionBuilderFlyout();
   });
 
+  it('Validates auto-suggested fields correctly', () => {
+    // open add exception modal
+    openExceptionFlyoutFromEmptyViewerPrompt();
+
+    // add exception item name
+    addExceptionFlyoutItemName('My item name');
+
+    // add an entry with a value and submit button should enable
+    addExceptionEntryFieldValue('agent.type', 0);
+    cy.get(VALUES_INPUT).eq(0).type(`{enter}`);
+    cy.get(VALUES_INPUT).eq(0).type(`{downarrow}{enter}`);
+    cy.get(CONFIRM_BTN).should('be.enabled');
+
+    closeExceptionBuilderFlyout();
+  });
+
   // TODO - Add back in error states into modal
   describe.skip('flyout errors', () => {
     beforeEach(() => {

x-pack/plugins/security_solution/public/common/containers/source/index.tsx

@@ -43,7 +43,7 @@ export const getAllFieldsByName = (
   keyBy('name', getAllBrowserFields(browserFields));
 
 export const getIndexFields = memoizeOne(
-  (title: string, fields: IndexField[]): DataViewBase =>
+  (title: string, fields: IndexField[], _includeUnmapped: boolean = false): DataViewBase =>
     fields && fields.length > 0
       ? {
           fields: fields.map((field) =>
@@ -63,7 +63,10 @@ export const getIndexFields = memoizeOne(
           title,
         }
       : { fields: [], title },
-  (newArgs, lastArgs) => newArgs[0] === lastArgs[0] && newArgs[1].length === lastArgs[1].length
+  (newArgs, lastArgs) =>
+    newArgs[0] === lastArgs[0] &&
+    newArgs[1].length === lastArgs[1].length &&
+    newArgs[2] === lastArgs[2]
 );
 
 /**
@@ -145,21 +148,24 @@ export const useFetchIndex = (
               if (isCompleteResponse(response)) {
                 Promise.resolve().then(() => {
                   ReactDOM.unstable_batchedUpdates(() => {
-                    const stringifyIndices = `${response.indicesExist
+                    const stringifyIndices = response.indicesExist.sort().join();
-                      .sort()
-                      .join()} (includeUnmapped: ${includeUnmapped})`;
 
                     previousIndexesName.current = response.indicesExist;
                     const { browserFields } = getDataViewStateFromIndexFields(
                       stringifyIndices,
-                      response.indexFields
+                      response.indexFields,
+                      includeUnmapped
                     );
                     setLoading(false);
                     setState({
                       browserFields,
                       indexes: response.indicesExist,
                       indexExists: response.indicesExist.length > 0,
-                      indexPatterns: getIndexFields(stringifyIndices, response.indexFields),
+                      indexPatterns: getIndexFields(
+                        stringifyIndices,
+                        response.indexFields,
+                        includeUnmapped
+                      ),
                     });
 
                     searchSubscription$.current.unsubscribe();

x-pack/plugins/security_solution/public/common/containers/source/use_data_view.tsx

@@ -50,7 +50,7 @@ interface DataViewInfo {
  * VERY mutatious on purpose to improve the performance of the transform.
  */
 export const getDataViewStateFromIndexFields = memoizeOne(
-  (_title: string, fields: IndexField[]): DataViewInfo => {
+  (_title: string, fields: IndexField[], _includeUnmapped: boolean = false): DataViewInfo => {
     // Adds two dangerous casts to allow for mutations within this function
     type DangerCastForMutation = Record<string, {}>;
 
@@ -78,7 +78,10 @@ export const getDataViewStateFromIndexFields = memoizeOne(
       }
     );
   },
-  (newArgs, lastArgs) => newArgs[0] === lastArgs[0] && newArgs[1].length === lastArgs[1].length
+  (newArgs, lastArgs) =>
+    newArgs[0] === lastArgs[0] &&
+    newArgs[1].length === lastArgs[1].length &&
+    newArgs[2] === lastArgs[2]
 );
 
 export const useDataView = (): {