[Cases] Guardrails getConnectors API (#161282)

Connected to https://github.com/elastic/kibana/issues/146945

## Summary

| Description  | Limit | Done? | Documented?
| ------------- | ---- | :---: | ---- |
| Total number of supported connectors returned | 1000 |
✅ | Yes |

### Checklist

Delete any items that are not applicable to this PR.

- [x]
[Documentation](https://www.elastic.co/guide/en/kibana/master/development-documentation.html)
was added for features that require explanation or tutorials
- [x] [Unit or functional
tests](https://www.elastic.co/guide/en/kibana/master/development-tests.html)
were updated or added to match the most common scenarios

### Release Notes

The getConnectors API will now limit the number of supported connectors
returned to 1000.

x-pack/plugins/cases/common/constants/index.ts

@@ -111,6 +111,7 @@ export const MAX_CATEGORY_FILTER_LENGTH = 100 as const;
 export const MAX_TAGS_FILTER_LENGTH = 100 as const;
 export const MAX_ASSIGNEES_FILTER_LENGTH = 100 as const;
 export const MAX_REPORTERS_FILTER_LENGTH = 100 as const;
+export const MAX_SUPPORTED_CONNECTORS_RETURNED = 1000 as const;
 
 /**
  * Validation

x-pack/plugins/cases/docs/openapi/bundled.json

@@ -1800,7 +1800,8 @@
                         "type": "integer"
                       }
                     }
-                  }
+                  },
+                  "maxItems": 1000
                 },
                 "examples": {
                   "findConnectorResponse": {

x-pack/plugins/cases/docs/openapi/bundled.yaml

@@ -1106,6 +1106,7 @@ paths:
                       type: string
                     referencedByCount:
                       type: integer
+                maxItems: 1000
               examples:
                 findConnectorResponse:
                   $ref: '#/components/examples/find_connector_response'

x-pack/plugins/cases/docs/openapi/paths/api@cases@configure@connectors@_find.yaml

@@ -14,10 +14,11 @@ get:
         application/json:
           schema:
             type: array
-            items: 
+            items:
               type: object
               properties:
                 $ref: '../components/schemas/connector_response_properties.yaml'
+            maxItems: 1000
           examples:
             findConnectorResponse:
               $ref: '../components/examples/find_connector_response.yaml'

x-pack/plugins/cases/server/client/configure/client.test.ts

@@ -10,6 +10,7 @@ import { actionsClientMock } from '@kbn/actions-plugin/server/mocks';
 import type { CasesClientArgs } from '../types';
 import { getConnectors, get, update } from './client';
 import { createCasesClientInternalMock, createCasesClientMockArgs } from '../mocks';
+import { MAX_SUPPORTED_CONNECTORS_RETURNED } from '../../../common/constants';
 
 describe('client', () => {
   const clientArgs = createCasesClientMockArgs();
@@ -219,6 +220,15 @@ describe('client', () => {
         },
       ]);
     });
+
+    it('limits connectors returned to 1000', async () => {
+      actionsClient.listTypes.mockImplementation(async () => actionTypes.slice(0, 1));
+      actionsClient.getAll.mockImplementation(async () =>
+        Array(MAX_SUPPORTED_CONNECTORS_RETURNED + 1).fill(connectors[0])
+      );
+
+      expect((await getConnectors(args)).length).toEqual(MAX_SUPPORTED_CONNECTORS_RETURNED);
+    });
   });
 
   describe('get', () => {

x-pack/plugins/cases/server/client/configure/client.ts

@@ -30,7 +30,10 @@ import {
 } from '../../../common/types/api';
 import type { ConnectorMappings, ConnectorMappingResponse } from '../../../common/api';
 import { FindActionConnectorResponseRt, decodeWithExcessOrThrow } from '../../../common/api';
-import { MAX_CONCURRENT_SEARCHES } from '../../../common/constants';
+import {
+  MAX_CONCURRENT_SEARCHES,
+  MAX_SUPPORTED_CONNECTORS_RETURNED,
+} from '../../../common/constants';
 import { createCaseError } from '../../common/error';
 import type { CasesClientInternal } from '../client_internal';
 import type { CasesClientArgs } from '../types';
@@ -207,9 +210,9 @@ export async function getConnectors({
       return types;
     }, {} as Record<string, ActionType>);
 
-    const res = (await actionsClient.getAll()).filter((action) =>
-      isConnectorSupported(action, actionTypes)
-    );
+    const res = (await actionsClient.getAll())
+      .filter((action) => isConnectorSupported(action, actionTypes))
+      .slice(0, MAX_SUPPORTED_CONNECTORS_RETURNED);
 
     return decodeOrThrow(FindActionConnectorResponseRt)(res);
   } catch (error) {