[ci] Don't run tests on internal pipeline builds

[radical]

Description

Tests for main are run on the public pipeline, and are not needed for the internal one where we essentially build the packages to be published.

Checklist

• Is this feature complete?
  • Yes. Ready to ship.
  • No. Follow-up changes expected.
• Are you including unit tests for the changes and scenario tests if relevant?
  • Yes
  • No
• Did you add public API?
  • Yes
    • If yes, did you have an API Review for it?
      • Yes
      • No
    • Did you add <remarks /> and <code /> elements on your triple slash comments?
      • Yes
      • No
  • No
• Does the change make any security assumptions or guarantees?
  • Yes
    • If yes, have you done a threat model and had a security review?
      • Yes
      • No
  • No
• Does the change require an update in our Aspire docs?
  • Yes
    • Link to aspire-docs issue:
  • No

Microsoft Reviewers: Open in CodeFlow

[radical]

Internal build - https://dev.azure.com/dnceng/internal/_build/results?buildId=2565704&view=results .

[radical]

@joperezr this one is ready for review.

[eerhardt]

LGTM. Thanks!

[joperezr]

Merging and backporting this to release/9.0 as it is needed for the internal builds too. Thanks @radical!

[joperezr]

/backport to release/9.0

[github-actions]

Started backporting to release/9.0: https://github.com/dotnet/aspire/actions/runs/11488497385