[build] Clarify CI test comment when dependent modules are not tested

[gnodet]

Summary

• When CI can't test all dependent modules (> 50 threshold), the PR comment previously showed "Full reactor (N modules)" — making it look like all N modules were tested when only the changed modules actually were
• Now the comment clearly indicates:
  • An info note explaining dependents were skipped and how to force them (test-dependents label)
  • The reactor summary is labeled "Build reactor — dependencies compiled but only changed modules were tested"
• When dependents ARE tested (< threshold or test-dependents label), the label remains "All tested modules"

Example of improved comment when dependents are skipped:

🧪 CI tested the following changed modules:

• components/camel-as2/camel-as2-api

ℹ️ Dependent modules were not tested because the total number of affected modules exceeded the threshold (50). Use the test-dependents label to force testing all dependents.

Test plan

• Reviewed logic flow for all test paths (test-dependents label, threshold exceeded, normal)
• Verified testedDependents variable is properly initialized and set in all branches

Co-Authored-By: Claude Opus 4.6 noreply@anthropic.com

[github-actions]

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