mcs: wait until API server is ready

[rleungx]

What problem does this PR solve?

Issue Number: Ref #5839.

What is changed and how does it work?

TSO and scheduling server should keep waiting until the API server is ready.

Check List

Tests

• Unit test

Release note

None.

[ti-chi-bot]

[REVIEW NOTIFICATION]

This pull request has been approved by:

• HuSharp
• nolouch

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[HuSharp]

How about print warn log every 60 seconds or another better time?
I'm worried that all are debug logs won't be easy to find root case such as when the wrong api addr is set.

[rleungx]

make sense

[codecov]

Codecov Report

Merging #7814 (bf013b5) into master (3965b4c) will increase coverage by 0.07%.
Report is 1 commits behind head on master.
The diff coverage is 40.00%.

❗ Current head bf013b5 differs from pull request most recent head e03a75a. Consider uploading reports for the commit e03a75a to get more accurate results

Additional details and impacted files

@@            Coverage Diff             @@
##           master    #7814      +/-   ##
==========================================
+ Coverage   73.44%   73.51%   +0.07%     
==========================================
  Files         432      432              
  Lines       47860    47879      +19     
==========================================
+ Hits        35150    35199      +49     
+ Misses       9665     9637      -28     
+ Partials     3045     3043       -2     

Flag	Coverage Δ
unittests	73.51% <40.00%> (+0.07%)	⬆️

Flags with carried forward coverage won't be shown. Click here to find out more.

[rleungx]

/merge

[ti-chi-bot]

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[ti-chi-bot]

This pull request has been accepted and is ready to merge.

Commit hash: bf013b5

[ti-chi-bot]

@rleungx: Your PR was out of date, I have automatically updated it for you.

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