GraphQL: Add gitlay field to CiStatusAction

What does this MR do?

Adds gitaly check for CiStatusAction. This blocks the next set of Pipeline Graph Restructure MRs (#276949 (closed)) because now the working code is returning an error.

For more discussion, see https://gitlab.slack.com/archives/C6MLS3XEU/p1606810122391200 (internal).

Does this MR meet the acceptance criteria?

Conformity

• Changelog entry
• Code review guidelines
• Merge request performance guidelines
• Style guides