[BR]initialize status metric to zero (#5637)

[ti-chi-bot]

This is an automated cherry-pick of #5637

What problem does this PR solve?

Currently when the federated manager restart we lost the metrics, and the new status metric will start with value 1. In our dashboard we are measuring success/fail backups by increase() function, current implementation will cause we lost the back up status when federated manager restarts.

This PR set the status counter to 0 before it emit the first metric.

What is changed and how does it work?

Code changes

• [x] Has Go code change
• [ ] Has CI related scripts change

Tests

• [ ] Unit test
• [ ] E2E test
• [x] Manual test
• [ ] No code

Side effects

• [ ] Breaking backward compatibility
• [ ] Other side effects:

Related changes

• [ ] Need to cherry-pick to the release branch
• [ ] Need to update the documentation

Release Notes

Please refer to Release Notes Language Style Guide before writing the release note.

[ti-chi-bot[bot]]

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