Set persist-credentials: false on every actions/checkout step, so the
job token is not left in .git/config for the rest of the job. No step
after checkout pushes or fetches with it. The only authenticated operation,
gh release in release.yml, uses GH_TOKEN.
Signed-off-by: David Barragán Merino <david.barragan@kaleidos.net>
The MCP workflow was named "MCP CI" while every other tests-*.yml
workflow uses the "CI: <Component>" pattern. Rename it to "CI: MCP"
for consistency in the GitHub Actions listing.
