VReplication Workflow: set state correctly when restarting workflow streams in the copy phase

[rohit-nayak-ps]

Description

This PR fixes a bug where a workflow which has been stopped during the copy phase has its published state (observable at debug/vars set incorrectly to Running when it is restarted. We now check for tables still pending copy and update the stream state to Copying or Running based on whether we are still in the copy phase.

Backports

This issue has been around for about 15 months, so backporting to all supported versions.

Related Issue(s)

#15337

Checklist

• "Backport to:" labels have been added if this change should be back-ported to release branches
• If this change is to be back-ported to previous releases, a justification is included in the PR description
• Tests were added or are not required
• Did the new or modified tests pass consistently locally and on CI?
• Documentation was added or is not required

Deployment Notes

[vitess-bot]

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[codecov]

Codecov Report

Attention: Patch coverage is 85.71429% with 2 lines in your changes missing coverage. Please review.

Project coverage is 68.56%. Comparing base (1ffabca) to head (c8a2de5).
Report is 1 commits behind head on main.

Files	Patch %	Lines
go/vt/vttablet/tabletmanager/rpc_vreplication.go	85.71%	2 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main   #16217      +/-   ##
==========================================
+ Coverage   68.55%   68.56%   +0.01%     
==========================================
  Files        1544     1544              
  Lines      197895   197909      +14     
==========================================
+ Hits       135658   135688      +30     
+ Misses      62237    62221      -16     

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