v5.0.7 regression: not detecting fork correctly anymore (maybe due to use of workflow_call)

[wdconinc]

As of presumably #1690, v5.0.7, we are noticing that the detection of forked repositories has ceased to function as before.

Before:

• GITHUB_EVENT_PULL_REQUEST_HEAD_LABEL: spack:dependabot/github_actions/codecov/codecov-action-5.0.3
• GITHUB_EVENT_PULL_REQUEST_REPO_FULL_NAME:
• GITHUB_REPOSITORY: spack/spack

After:

• GITHUB_EVENT_PULL_REQUEST_HEAD_LABEL: spack:dependabot/github_actions/codecov/codecov-action-5.0.7
• GITHUB_EVENT_PULL_REQUEST_HEAD_REPO_FULL_NAME: spack/spack
• GITHUB_REPOSITORY: spack/spack

Diff:

  GITHUB_EVENT_PULL_REQUEST_HEAD_LABEL: spack:dependabot/github_actions/codecov/codecov-action-5.0.7
- GITHUB_EVENT_PULL_REQUEST_REPO_FULL_NAME: 
+ GITHUB_EVENT_PULL_REQUEST_HEAD_REPO_FULL_NAME: spack/spack
  GITHUB_REPOSITORY: spack/spack

Since we call this as a workflow_call, the codecov-actions for the fork runs with the upstream GITHUB_REPOSITORY. The test [ "${GITHUB_EVENT_PULL_REQUEST_HEAD_REPO_FULL_NAME}" != "$GITHUB_REPOSITORY" ] fails, where previously [ "${GITHUB_EVENT_PULL_REQUEST_REPO_FULL_NAME}" != "$GITHUB_REPOSITORY" ] used to succeed and result in TOKENLESS getting set.

It appears that the previous behavior may have been unintentional since GITHUB_EVENT_PULL_REQUEST_REPO_FULL_NAME was empty, and #1690 fixed that.

It is possible this is related to #1705, but we do not see any issues with curl calls, and we are using workflow_call which may affect how the event is passed (though the docs indicate that the original pull_request event payload is forwarded).

Ref: spack/spack#47732.