Adding ability to deselect EPM subcategory (#164260)

## Summary

Fixes #156419 

If an EPM subcategory is selected, this PR makes it possible to deselect
that subcategory before deselecting the parent category by clicking on
the search bar button.

Behavior is shown in below video:

49e20b81-1a3e-436e-8b94-af43a515eccf

### Checklist

Delete any items that are not applicable to this PR.

- [x] Any UI touched in this PR is usable by keyboard only (learn more
about [keyboard accessibility](https://webaim.org/techniques/keyboard/))
- [x] Any UI touched in this PR does not create any new axe failures
(run axe in browser:
[FF](https://addons.mozilla.org/en-US/firefox/addon/axe-devtools/),
[Chrome](https://chrome.google.com/webstore/detail/axe-web-accessibility-tes/lhdoppojpmngadmnindnejefpokejbdd?hl=en-US))
- [x] This was checked for [cross-browser
compatibility](https://www.elastic.co/support/matrix#matrix_browsers)

### For maintainers

- [x] This was checked for breaking API changes and was [labeled
appropriately](https://www.elastic.co/guide/en/kibana/master/contributing.html#kibana-release-notes-process)

Co-authored-by: Kibana Machine <42973632+kibanamachine@users.noreply.github.com>
Co-authored-by: Julia Bardi <90178898+juliaElastic@users.noreply.github.com>

x-pack/plugins/fleet/public/applications/integrations/sections/epm/components/package_list_grid/search_box.tsx

@@ -54,6 +54,24 @@ export const SearchBox: FunctionComponent<Props> = ({
     });
   };
 
+  const onCategoryButtonClick = () => {
+    if (selectedSubCategory) {
+      if (setSelectedSubCategory) setSelectedSubCategory(undefined);
+      setUrlandReplaceHistory({
+        categoryId: selectedCategory,
+        subCategoryId: '',
+      });
+    } else {
+      setCategory('');
+      if (setSelectedSubCategory) setSelectedSubCategory(undefined);
+      setUrlandReplaceHistory({
+        searchString: '',
+        categoryId: '',
+        subCategoryId: '',
+      });
+    }
+  };
+
   const selectedCategoryTitle = selectedCategory
     ? categories.find((category) => category.id === selectedCategory)?.title
     : undefined;
@@ -100,15 +118,7 @@ export const SearchBox: FunctionComponent<Props> = ({
             {getCategoriesLabel}
             <button
               data-test-subj="epmList.categoryBadge.closeBtn"
-              onClick={() => {
-                setCategory('');
-                if (setSelectedSubCategory) setSelectedSubCategory(undefined);
-                setUrlandReplaceHistory({
-                  searchString: '',
-                  categoryId: '',
-                  subCategoryId: '',
-                });
-              }}
+              onClick={onCategoryButtonClick}
               aria-label="Remove filter"
               style={{
                 padding: euiTheme.size.xs,