sagemathgh-36496: build*.yml: Fix application of CI fixes broken in sagemath#36442
    
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Fixes the failure as seen e.g. in https://github.com/sagemath/sage/actio
ns/runs/6599334101/job/17928255227?pr=36271#step:7:8
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URL: sagemath#36496
Reported by: Matthias Köppe
Reviewer(s): Kwankyu Lee

Author: Release Manager

.ci/retrofit-worktree.sh

@@ -12,6 +12,10 @@ export GIT_AUTHOR_EMAIL="[email protected]"
 export GIT_COMMITTER_NAME="$GIT_AUTHOR_NAME"
 export GIT_COMMITTER_EMAIL="$GIT_AUTHOR_EMAIL"
 
+# Set globally for other parts of the workflow
+git config --global user.name "$GIT_AUTHOR_NAME"
+git config --global user.email "$GIT_AUTHOR_EMAIL"
+
 set -ex
 
 # If actions/checkout downloaded our source tree using the GitHub REST API