Reapply "[ci] Revert org-wide commit status checks (#195954)" (#205546)

Previously reverted due to the number of statuses we were tracking, and
the subsequent rate limiting.

The number of updates we need to do after
#199073 is significantly lower.
We've already been using org-wide status checks for [on-merge commit
statuses](https://github.com/elastic/kibana/commits/main) in the interim
and are not seeing issues.

Author: jbudz

.buildkite/pipeline-resource-definitions/kibana-pr.yml

@@ -20,7 +20,7 @@ spec:
     spec:
       env:
         ELASTIC_PR_COMMENTS_ENABLED: 'true'
-        GITHUB_BUILD_COMMIT_STATUS_ENABLED: 'true'
+        ELASTIC_GITHUB_BUILD_COMMIT_STATUS_ENABLED: 'true'
         GITHUB_BUILD_COMMIT_STATUS_CONTEXT: kibana-ci
       allow_rebuilds: true
       branch_configuration: ''

.buildkite/pipelines/serverless_deployment/project-build-and-deploy-pr.yml

@@ -1,6 +1,6 @@
 env:
   ELASTIC_PR_COMMENTS_ENABLED: 'true'
-  GITHUB_BUILD_COMMIT_STATUS_ENABLED: 'true'
+  ELASTIC_GITHUB_BUILD_COMMIT_STATUS_ENABLED: 'true'
   GITHUB_BUILD_COMMIT_STATUS_CONTEXT: kibana-deploy-project-from-pr
 
 steps: