Support TropiBot dispatch fallbacks in staking tests - #3

Summary:

• Add repository_dispatch client_payload fallbacks for checkout refs in staking sync and attestation reusable workflows.
• Add client_payload PR-number fallbacks for test-runner reporting.

Notes:

• Package repos still need wrapper workflows with repository_dispatch types tropibot-sync-test and tropibot-attestation-test.

Tests:

• git diff --check