Fix AzureCommentReporter not adding comments to PR

[lukelloyd1985]

Fixes #4132

Proposed Changes

Use SYSTEM_PULLREQUEST_SOURCEREPOSITORYURI instead of BUILD_REPOSITORY_ID to locate the correct repository referenced in the PR.

Fallback to BUILD_REPOSITORY_ID if SYSTEM_PULLREQUEST_SOURCEREPOSITORYURI isn't available to avoid a breaking change.

Readiness Checklist

Author/Contributor

• Add entry to the CHANGELOG listing the change and linking to the corresponding issue (if appropriate)
• If documentation is needed for this change, has that been included in this pull request

Reviewing Maintainer

• Label as breaking if this is a large fundamental change
• Label as either automation, bug, documentation, enhancement, infrastructure, or performance

[echoix]

Ill still let @nvuillam go through as I didn't follow attentively.

[lukelloyd1985]

@nvuillam, are we able to merge this PR and hopefully a new image creation succeeds 🤞🏻

[nvuillam]

@lukelloyd1985 trivy is still unstable... but some flavor beta images has been successfully created and uploaded :)

https://github.com/oxsecurity/megalinter/actions/runs/11383553685