set all metrics to 0 for unregistered quorums

[shrimalmadhur]

Why are these changes needed?

• Currently if someone deregisters then the metrics for rank and stake share are set to previous value. Which doesn't help operators with real data and they see wrong graph
• This way we set those unregistered operator metrics to 0.
• When node restarts all the metrics will be cleared and cache will build again

please verify if logic looks sane

Checks

• I've made sure the lint is passing in this PR.
• I've made sure the tests are passing. Note that there might be a few flaky tests, in that case, please comment that they are not relevant.
• Testing Strategy
  • Unit tests
  • Integration tests
  • This PR is not tested :(