Stale update status cache causes false "not secure" warnings during Pantheon deploy checks

[balagan73]

Closes #1058

Summary

• deployCheckRequirementErrors() runs drush rq as the last step of a Pantheon deploy, but Drush CLI calls never match a Drupal route, so UpdateManager::projectStorage() always serves its stale cached update_project_projects data instead of recomputing it against the code just deployed.
• This can produce false "Not secure!" warnings for a module/core version that was in fact the one just deployed.
• Fix: clear the update_project_projects key in the update keyvalue-expirable store via terminus remote:drush ... -- php:eval in its own exec stack, immediately before the rq check, so the comparison is always computed fresh.

Test plan

• ddev phpstan — no errors
• Verified the exact eval command locally with ddev drush: populated the update_project_projects key via Drupal::service('update.manager')->getProjects(), ran the delete command, confirmed the key was removed from keyValueExpirable('update')
• Not yet verified end-to-end against a live Pantheon deploy (requires terminus auth not available in this environment)

🤖 Generated with Claude Code

TB: 0.7/1h

[amitaibu]

Can you please show a screenshot of how it looks before and after

[balagan73]

This is what we have now. In another project when we did the update, we got a false positive: