Mute failing API key integration test (elastic#38409)

This commit mutes the test
testGetAndInvalidateApiKeysWithExpiredAndInvalidatedApiKey as it failed
during a PR build.

x-pack/plugin/security/src/test/java/org/elasticsearch/xpack/security/authc/ApiKeyIntegTests.java

@@ -232,6 +232,7 @@ public void testInvalidateApiKeysForApiKeyName() throws InterruptedException, Ex
         verifyInvalidateResponse(1, responses, invalidateResponse);
     }
 
+    @AwaitsFix(bugUrl = "https://github.com/elastic/elasticsearch/issues/38408")
     public void testGetAndInvalidateApiKeysWithExpiredAndInvalidatedApiKey() throws Exception {
         List<CreateApiKeyResponse> responses = createApiKeys(1, null);
         Instant created = Instant.now();