Ignore .git directory in switch_prow_jobs_fr_branch.sh

Update the find command to exclude the .git directory when searching
for files matching "18.0-fr" pattern. This prevents attempting to
process files in the git repository metadata.

Changes:
- Add `-name .git -prune` to skip .git directory
- Add `-type f` to only match files (not directories)
- Use `-o -print` to print matching files

Co-Authored-By: Claude Sonnet 4.5 <noreply@anthropic.com>

Author: stuggi

switch_prow_jobs_fr_branch.sh

@@ -12,7 +12,7 @@ set -ex
 CURRENT=$1
 NEXT=$2
 
-for X in $(find . | grep 18.0-fr); do
+for X in $(find . -name .git -prune -o -type f -print | grep 18.0-fr); do
     #rename the file (NOTE: prow jobs require frX in the name)
     NEW_FILE=$(echo $X | sed -e "s|$CURRENT|$NEXT|")
     git mv $X $NEW_FILE