Add weekly scheduled CI workflow

[Copilot]

Pipeline checks weren't running reliably due to infrequent commits. This adds a scheduled workflow to ensure CI runs regularly regardless of commit activity.

Changes

• Add a weekly Monday 08:00 UTC scheduled trigger to the Azure Pipelines definition (1es-azure-pipeline.yml) for the main branch.
• Ensure the scheduled run executes regardless of recent changes (always: true).

[Copilot]

Pull request overview

This PR aims to ensure CI runs regularly even when commits are infrequent by introducing a weekly scheduled run. In the current diff, this is implemented as an Azure Pipelines scheduled trigger (not as a new GitHub Actions workflow as stated in the PR description).

Changes:

• Add a weekly Monday 08:00 UTC scheduled trigger to the Azure Pipelines definition (1es-azure-pipeline.yml) for the main branch.
• Ensure the scheduled run executes regardless of recent changes (always: true).

[nagilson]

Is the code QL flagger upset because of the PR builds, the CI builds, or both? This only builds on the internal CI build; the pr yml is 1pr-azure-pipeline.

[nagilson]

Codeql.Enabled: true is set on both pipelines: the internal CI build (1es-azure-pipeline.yml, def 656) and the public PR build (1pr-azure-pipeline.yml, def 60), so CodeQL runs in both. To make sure the scan runs on a regular cadence regardless of commit/PR activity, I've now added the same weekly Monday 08:00 UTC schedule to 1pr-azure-pipeline.yml as well, so it fires on both the CI and PR yamls.

[Copilot]

Pull request overview

Copilot reviewed 2 out of 2 changed files in this pull request and generated 1 comment.

[marcpopMSFT]

Codeql.Enabled: true is set on both pipelines: the internal CI build (1es-azure-pipeline.yml, def 656) and the public PR build (1pr-azure-pipeline.yml, def 60), so CodeQL runs in both. To make sure the scan runs on a regular cadence regardless of commit/PR activity, I've now added the same weekly Monday 08:00 UTC schedule to 1pr-azure-pipeline.yml as well, so it fires on both the CI and PR yamls.

@nagilson codeql is only required to run once a month on CI. I don't think it hurts us to include it in the PR builds as well but it's not a requirement fyi.

Also, we now need a third person to review this.