fix(ci): new PR comments cancel ongoing ephemeral builds

[dpgaspar]

SUMMARY

Currently ongoing ephemeral env builds can be canceled by new comments on a PR. Although the build is re-triggered again this can cause confusion and certainly delays on spinning up new ephemeral environments.

This is probably caused by the global concurrency group, splitting this group between comments and build should fix this issue.

Unfortunately it's hard to test this at the PR level since this workflow code will always use the latest commit on the default branch 

BEFORE/AFTER SCREENSHOTS OR ANIMATED GIF

TESTING INSTRUCTIONS

ADDITIONAL INFORMATION

• Has associated issue:
• Required feature flags:
• Changes UI
• Includes DB Migration (follow approval process in SIP-59)
  • Migration is atomic, supports rollback & is backwards-compatible
  • Confirm DB migration upgrade and downgrade tested
  • Runtime estimates and downtime expectations provided
• Introduces new feature or API
• Removes existing feature or API

[dpgaspar]

/testenv up

[dpgaspar]

test comment

[dpgaspar]

test comment

[kgabryje]

test comment