Lower the allowed Gitaly call count to 30

What does this MR do?

By lowering the allowed Gitaly call count, we should be able to detect N + 1 calls sooner. Also detects at least one more actual N + 1 RPC call.

What are the relevant issue numbers?

Part of: gitaly#1504

Does this MR meet the acceptance criteria?

• [-] Changelog entry added, if necessary
• [-] Documentation created/updated via this MR
• [-] Documentation reviewed by technical writer or follow-up review issue created
• [-] Tests added for this feature/bug
• [-] Tested in all supported browsers
• [-] Conforms to the code review guidelines
• [-] Conforms to the merge request performance guidelines
• [-] Conforms to the style guides
• [-] Conforms to the database guides
• [-] Link to e2e tests MR added if this MR has Requires e2e tests label. See the Test Planning Process.
• [-] Security reports checked/validated by reviewer