Fix interactive Setup UI never reaches Finished state (#165273)

Resolves #162518

This PR updates the logic that detects whether Kibana has booted
correctly during interactive setup.

The issue described in #162518 was a false positive and only effected
Kibana when run in development mode.

We already have end-to-end tests which go through the entire enrollment
flow and ensure that Kibana correctly redirects to the login page once
interactive setup completes:

https://github.com/elastic/kibana/blob/main/test/interactive_setup_functional/tests/enrollment_token.ts#L78-L81

These tests passed with both the previous and the updated logic.
However, the end-to-end tests do not check development mode which is why
the build never failed and we started seeing this issue.

src/plugins/interactive_setup/public/progress_indicator.tsx

@@ -27,14 +27,7 @@ function isKibanaPastPreboot(response?: Response, body?: StatusResponse) {
   if (!response?.headers.get('content-type')?.includes('application/json')) {
     return false;
   }
-
-  return (
-    // Status endpoint may require authentication after `preboot` stage.
-    response?.status === 401 ||
-    // We're only interested in the availability of the critical core services.
-    (body?.status?.core?.elasticsearch?.level === 'available' &&
-      body?.status?.core?.savedObjects?.level === 'available')
-  );
+  return body?.status?.overall?.level === 'available';
 }
 
 export const ProgressIndicator: FunctionComponent<ProgressIndicatorProps> = ({ onSuccess }) => {

x-pack/test_serverless/functional/test_suites/common/index.ts

@@ -13,6 +13,7 @@ export default function ({ loadTestFile }: FtrProviderContext) {
     loadTestFile(require.resolve('./management'));
 
     // platform security
+    loadTestFile(require.resolve('./security/api_keys'));
     loadTestFile(require.resolve('./security/navigation/avatar_menu'));
 
     // Management