Investigation: whitespace-only change to trigger CLI E2E run

This is a no-op whitespace change (one trailing newline appended to
docs/ci/TestingOnCI.md) to trigger a CI run so we can observe the
'Unknown' CLI E2E test results that the workflow posts back as a PR
comment.

This commit intentionally makes no functional changes. It exists only
so this PR has something to push and so CI runs against it for
investigative purposes. See PR description for the analysis of what
causes the 'Unknown' results and what we plan to do about them.

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

Author: mitchdenny

docs/ci/TestingOnCI.md

@@ -411,3 +411,4 @@ pwsh eng/scripts/expand-test-matrix-github.ps1 `
   -CanonicalMatrixFile artifacts/canonical-test-matrix.json `
   -OutputMatrixFile artifacts/github-matrix.json
 ```
+