[release-23.0] workflow: finish switch traffic after post-journal cancel (#19672)

[vitess-bot]

Description

This is a backport of #19672

[codecov]

Codecov Report

❌ Patch coverage is 75.00000% with 6 lines in your changes missing coverage. Please review.
✅ Project coverage is 70.74%. Comparing base (550459d) to head (641aefa).
⚠️ Report is 8 commits behind head on release-23.0.

Files with missing lines	Patch %	Lines
go/vt/vtctl/workflow/server.go	75.00%	6 Missing ⚠️

Additional details and impacted files

@@                Coverage Diff                @@
##           release-23.0   #19682       +/-   ##
=================================================
+ Coverage         69.45%   70.74%    +1.29%     
=================================================
  Files              1607       22     -1585     
  Lines            215090     7528   -207562     
=================================================
- Hits             149397     5326   -144071     
+ Misses            65693     2202    -63491     

Flag	Coverage Δ
partial	70.74% <75.00%> (?)

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