fix(ci): Remove obsolete .gitmodules SSH-to-HTTPS rewrite steps

The rr-backend repo already uses HTTPS URLs in .gitmodules, so the sed
rewrite is a no-op. The subsequent git commit then fails with "nothing
to commit", breaking both test-ui-tests-rr and rr-backend-tests.

The git config URL rewrites (insteadOf) already handle authenticated
cloning, making the .gitmodules file modification unnecessary.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

Author: zah

.github/workflows/cross-repo-tests.yml

@@ -77,17 +77,6 @@ jobs:
           path: ${{ github.workspace }}/../codetracer-rr-backend
           gh-token: ${{ secrets.GH_READ_METACRAFT_PRIVATE_REPOS }}
 
-      # Rewrite .gitmodules SSH URLs to HTTPS so nix's internal git fetcher
-      # can resolve submodules when evaluating the flake with submodules=1.
-      - name: Rewrite rr-backend .gitmodules for nix
-        run: |
-          CLONE_DIR="$(pwd)/../codetracer-rr-backend"
-          cd "$CLONE_DIR"
-          sed -i 's|git@github.com:|https://github.com/|g' .gitmodules
-          sed -i 's|ssh://git@github.com/|https://github.com/|g' .gitmodules
-          git add .gitmodules
-          git -c user.name="CI" -c user.email="ci@local" commit --no-gpg-sign -m "CI: rewrite submodule URLs to HTTPS"
-
       - name: Build ct-rr-support
         run: |
           CLONE_DIR="$(pwd)/../codetracer-rr-backend"

ci/setup-rr-backend.sh

@@ -89,14 +89,6 @@ clone_rr_backend() {
 			git config "$url" "$new_url"
 		done
 		git submodule update --recursive
-
-		# Rewrite .gitmodules SSH URLs to HTTPS so nix's internal git fetcher
-		# can resolve submodules when evaluating the flake with submodules=1
-		sed -i 's|git@github.com:|https://github.com/|g' .gitmodules
-		sed -i 's|ssh://git@github.com/|https://github.com/|g' .gitmodules
-		# Stage and commit the rewrite so nix sees it in the git tree
-		git add .gitmodules
-		git -c user.name="CI" -c user.email="ci@local" commit --no-gpg-sign -m "CI: rewrite submodule URLs to HTTPS"
 	)
 }