API: Make Deployments responses more consistent

Summary

As noted in !19658 (comment 244220800), the List Project Deployments API endpoint may not always return the same results. It requires some sort of ordering clause for consistency.

Improvements

Adding id desc as a tie-breaker should work.

Risks

Risk of unexpected query side-effects should be minimal.

Involved components

• lib/api/deployments.rb

Questions

Is there a solution that could be easily applied to other API endpoints that lack a consistency mechanism?