Revert "Adjust way to get changed files (#8709)"

This reverts commit 7dc621f.

Author: sarahchen6

.circleci/config.continue.yml.j2

@@ -167,8 +167,7 @@ commands:
               if [[ "$BRANCH" != "master" ]] && [[ "$BRANCH" != "release/*" ]]; then
                 # We know that we have checked out the PR merge branch, so the HEAD commit is a merge
                 # As a backup, if anything goes wrong with the diff, the build will fail
-                # Get list of changed files directly using git diff-tree to avoid issues with large binary files
-                CHANGED_FILES=$(git diff-tree --no-commit-id --name-only -r HEAD)
+                CHANGED_FILES=$(git show HEAD | grep -e "^Merge:" | cut -d ' ' -f 2- | sed 's/ /.../' | xargs git diff --name-only)
                 # Count the number of matches, and ignore if the grep doesn't match anything
                 MATCH_COUNT=$(echo "$CHANGED_FILES" | grep -c -E "<< pipeline.parameters.global_pattern >>|<< parameters.pattern >>") || true
                 if [[ "$MATCH_COUNT" -eq "0" ]]; then