Relocated shortcut for proposer refresh

[jeongkyun-oh]

Proposed changes

Refresh method relates to the validators, demotedValidators, and proposers.
The validators and demotedValidators should be updated although the proposers are calculated already, so the refresh proposers short cut logic is moved.

This resolves the problem where the validator is not demoted right after the addvalidator vote.

Types of changes

Please put an x in the boxes related to your change.

• Bugfix
• New feature or enhancement
• Others

Checklist

Put an x in the boxes that apply. You can also fill these out after creating the PR. If you're unsure about any of them, don't hesitate to ask. We're here to help! This is simply a reminder of what we are going to look for before merging your code.

• I have read the CONTRIBUTING GUIDELINES doc
• I have signed the CLA
• Lint and unit tests pass locally with my changes ($ make test)
• I have added tests that prove my fix is effective or that my feature works
• I have added necessary documentation (if appropriate)
• Any dependent changes have been merged and published in downstream modules

[yoomee1313]

lgtm!