Always run the latest tools PR checks so we can make them required

[henrymercer]

This change runs integration tests with all three bundles, even if tools: latest would be the same as tools: null (i.e. omitting the tools property). This allows us to make integration tests against each one of these three tools configurations required status checks on PRs.

As future work, we could move the "$CODEQL_VERSION_DEFAULT" == "$CODEQL_VERSION_LATEST" logic into jobs running with tools: latest to minimise redundant work, or investigate depending on statuses rather than Actions jobs. However right now the additional cost created by these redundant jobs doesn't seem to justify the complexity.

Merge / deployment checklist

• Confirm this change is backwards compatible with existing workflows.
• Confirm the readme has been updated if necessary.
• Confirm the changelog has been updated if necessary.

[edoardopirovano]

LGTM