cluster: fix tiflash uptime

[nexustar]

What problem does this PR solve?

• fix Can't display tiflash uptime  #2224

What is changed and how it works?

Check List

Tests

• Unit test
• Integration test
• Manual test (add detailed scripts or steps below)
• No code

Code changes

• Has exported function/method change
• Has exported variable/fields change
• Has interface methods change
• Has persistent data change

Side effects

• Possible performance regression
• Increased code complexity
• Breaking backward compatibility

Related changes

• Need to cherry-pick to the release branch
• Need to update the documentation

Release notes:

NONE

[codecov-commenter]

Codecov Report

Patch coverage: 46.67% and project coverage change: -0.18 ⚠️

Comparison is base (c2ae2f6) 56.20% compared to head (b4ba19e) 56.02%.

❗ Current head b4ba19e differs from pull request most recent head d9d866a. Consider uploading reports for the commit d9d866a to get more accurate results

Additional details and impacted files

@@            Coverage Diff             @@
##           master    #2227      +/-   ##
==========================================
- Coverage   56.20%   56.02%   -0.18%     
==========================================
  Files         320      320              
  Lines       33683    33685       +2     
==========================================
- Hits        18931    18870      -61     
- Misses      12489    12547      +58     
- Partials     2263     2268       +5     

Flag	Coverage Δ
cluster	45.06% <46.67%> (-0.19%)	⬇️
dm	25.98% <0.00%> (-0.05%)	⬇️
playground	15.70% <ø> (-0.02%)	⬇️
tiup	15.94% <ø> (-0.02%)	⬇️
unittest	22.69% <0.00%> (+0.01%)	⬆️

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

Impacted Files	Coverage Δ
pkg/cluster/operation/check.go	47.61% <0.00%> (ø)
pkg/cluster/operation/systemd.go	61.70% <42.31%> (-24.66%)	⬇️
pkg/cluster/manager/display.go	51.17% <100.00%> (+0.45%)	⬆️

... and 10 files with indirect coverage changes

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[ti-chi-bot]

[APPROVALNOTIFIER] This PR is APPROVED

This pull-request has been approved by: kaaaaaaang

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• OWNERS [kaaaaaaang]

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[ti-chi-bot]

[LGTM Timeline notifier]

Timeline:

• 2023-07-13 09:39:12.007036942 +0000 UTC m=+584043.777375642: ☑️ agreed by kaaaaaaang.