fix: prevent infinite rerenders in useIncomingWebhooks (#6176)

React can sometimes be non-intuitive and behave erratically due to the
way it detects changes in hook dependencies.

This prevents infinite re-renders from `useIncomingWebhooks` by using a
static `DEFAULT_DATA` constant, so that its reference is always the
same, so no changes are detected when there are none.

Unrelated scouting, but this PR also removes an unneeded dependency in
the memoized columns in `ProjectActionsTable`.

frontend/src/component/project/Project/ProjectSettings/ProjectActions/ProjectActionsTable/ProjectActionsTable.tsx

@@ -182,7 +182,7 @@ export const ProjectActionsTable = ({
                 disableSortBy: true,
             },
         ],
-        [actions, incomingWebhooks, serviceAccounts],
+        [incomingWebhooks, serviceAccounts],
     );
 
     const [initialState] = useState({

frontend/src/hooks/api/getters/useIncomingWebhooks/useIncomingWebhooks.ts

@@ -8,13 +8,17 @@ import { useUiFlag } from 'hooks/useUiFlag';
 
 const ENDPOINT = 'api/admin/incoming-webhooks';
 
+const DEFAULT_DATA = {
+    incomingWebhooks: [],
+};
+
 export const useIncomingWebhooks = () => {
     const { isEnterprise } = useUiConfig();
     const incomingWebhooksEnabled = useUiFlag('incomingWebhooks');
 
     const { data, error, mutate } = useConditionalSWR(
         isEnterprise() && incomingWebhooksEnabled,
-        { incomingWebhooks: [] },
+        DEFAULT_DATA,
         formatApiPath(ENDPOINT),
         fetcher,
     );