mcs: fix the last heartbeat is not updated

[rleungx]

What problem does this PR solve?

Issue Number: Close #7445.

What is changed and how does it work?

Previous PR #7396 removed the process of updating the last heartbeat ts for the scheduling server, which led to the store disconnection. This PR adds it back.

Check List

Tests

• Manual test

Release note

None.

[ti-chi-bot]

[REVIEW NOTIFICATION]

This pull request has been approved by:

• CabinfeverB
• lhy1024

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[codecov]

Codecov Report

Merging #7450 (e71741c) into master (58e9b20) will decrease coverage by 0.02%.
Report is 2 commits behind head on master.
The diff coverage is 100.00%.

❗ Current head e71741c differs from pull request most recent head 7914742. Consider uploading reports for the commit 7914742 to get more accurate results

Additional details and impacted files

@@            Coverage Diff             @@
##           master    #7450      +/-   ##
==========================================
- Coverage   74.25%   74.24%   -0.02%     
==========================================
  Files         451      451              
  Lines       49587    49587              
==========================================
- Hits        36820    36814       -6     
- Misses       9470     9472       +2     
- Partials     3297     3301       +4     

Flag	Coverage Δ
unittests	74.24% <100.00%> (-0.02%)	⬇️

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[rleungx]

/merge

[ti-chi-bot]

@rleungx: It seems you want to merge this PR, I will help you trigger all the tests:

/run-all-tests

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[ti-chi-bot]

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

Commit hash: e71741c

[ti-chi-bot]

@rleungx: Your PR was out of date, I have automatically updated it for you.

If the CI test fails, you just re-trigger the test that failed and the bot will merge the PR for you after the CI passes.

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