Fix CLI exec with workflow matrix feature, where variables are not substituted.

[6543]

woodpecker-cli exec workflow-with-matrix.yaml is broken, variables are not substituted.

this sets m.Workflow at the end resets the previous set axis data

[6543]

source: https://codeberg.org/saces/woodpecker/commit/130d430d31a3e3170bfee71a86a995769a8b9c97

[woodpecker-bot]

Surge PR preview deployment succeeded. View it at https://woodpecker-ci-woodpecker-pr-6162.surge.sh

[codecov]

Codecov Report

❌ Patch coverage is 0% with 3 lines in your changes missing coverage. Please review.
✅ Project coverage is 31.98%. Comparing base (05f55fb) to head (987a79b).
⚠️ Report is 1 commits behind head on main.

Files with missing lines	Patch %	Lines
cli/exec/metadata.go	0.00%	2 Missing and 1 partial ⚠️

Additional details and impacted files

@@           Coverage Diff           @@
##             main    #6162   +/-   ##
=======================================
  Coverage   31.98%   31.98%           
=======================================
  Files         423      423           
  Lines       28568    28568           
=======================================
  Hits         9138     9138           
  Misses      18587    18587           
  Partials      843      843           

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