[refactor](cloud) Use unified function to refresh instance info

[w41ter]

What problem does this PR solve?

Issue Number: close #xxx

Related PR: #xxx

Problem Summary:

Release note

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Check List (For Author)

• Test

  • Regression test
  • Unit Test
  • Manual test (add detailed scripts or steps below)
  • No need to test or manual test. Explain why:
    • This is a refactor/code format and no logic has been changed.
    • Previous test can cover this change.
    • No code files have been changed.
    • Other reason

• Behavior changed:

  • No.
  • Yes.

• Does this need documentation?

  • No.
  • Yes.

Check List (For Reviewer who merge this PR)

• Confirm the release note
• Confirm test cases
• Confirm document
• Add branch pick label

[hello-stephen]

Thank you for your contribution to Apache Doris.
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Please clearly describe your PR:

1. What problem was fixed (it's best to include specific error reporting information). How it was fixed.
2. Which behaviors were modified. What was the previous behavior, what is it now, why was it modified, and what possible impacts might there be.
3. What features were added. Why was this function added?
4. Which code was refactored and why was this part of the code refactored?
5. Which functions were optimized and what is the difference before and after the optimization?

[w41ter]

run buildall

[hello-stephen]

Cloud UT Coverage Report

Increment line coverage 63.64% (7/11) 🎉

Increment coverage report
Complete coverage report

Category	Coverage
Function Coverage	79.74% (1267/1589)
Line Coverage	65.47% (21296/32526)
Region Coverage	66.88% (10769/16101)
Branch Coverage	56.58% (5676/10032)

[gavinchou]

there (the original impl. also) may be a bug that before L499 is called there could be another MS update the instancePB in KV, however the possibility is very low and seems will never happen:

1. call to L449 is very fast, in microsecs
2. the remote MS update will trigger a refresh_signal to all other instance, which make all MS eventually consistent

CC @deardeng

[gavinchou]

LGTM

[github-actions]

PR approved by at least one committer and no changes requested.

[github-actions]

PR approved by anyone and no changes requested.