Boost: Fix speed scores refreshing on cornerstone pages update

[dilirity]

Fixes HOG-223

Proposed changes:

• Check if Critical CSS module is active before marking Critical CSS as "needs update", forcing it to refresh speed scores.

Other information:

• Have you written new tests for your changes, if applicable?
• Have you checked the E2E test CI results, and verified that your changes do not break them?
• Have you tested your changes on WordPress.com, if applicable (if so, you'll see a generated comment below with a script to run)?

Jetpack product discussion

n/a

Does this pull request change what data or activity we track or use?

no

Testing instructions:

• Setup this branch and enable Boost;
• Keep Critical CSS and LCP disabled;
• Wait for Speed Scores to load;
• Update the Cornerstone Pages list - Speed Scores shouldn't refresh;
• Enable Critical CSS and wait for Speed Scores to load;
• Update the Cornerstone Pages list and wait for Critical CSS to complete regenerating. Speed Scores should refresh after that.

[github-actions]

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[jp-launch-control]

Code Coverage Summary

No summary data is available for parent commit 1667418, so cannot calculate coverage changes. 😴

If that commit is a feature branch rather than a trunk commit, this is expected. Otherwise, this should be updated once coverage for 1667418 is available.

Full summary · PHP report · JS report

_{Coverage check overridden by I don't care about code coverage for this PR Use this label to ignore the check for insufficient code coveage. .}

[kraftbj]

Works like a charm. Let's merge.