Simplify the synapse-usage-exporter git ownership fix

The recursive chown in front of the git task already guarantees that git
operates on a checkout owned by the user it becomes, so marking the path
as a safe.directory on top of that protects against nothing. Drop the
environment variables and condense the comment to a single line.

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>

roles/custom/matrix-synapse-usage-exporter/tasks/setup_install.yml

@@ -43,11 +43,7 @@
 
 - when: "matrix_synapse_usage_exporter_container_image_self_build | bool"
   block:
-    # A repository left behind with different file ownership (e.g. cloned by another user in the past)
-    # would make the git update below fail, either with a permission error or with git's
-    # dubious-ownership protection kicking in (which manifests as a confusing
-    # "'origin' does not appear to be a git repository" error, because git ignores
-    # the repository's own configuration in that case).
+    # A checkout owned by a different user (a uid change, an earlier clone by another user, etc.) would make the git task below fail on ownership or permissions.
     - name: Ensure synapse-usage-exporter repository ownership is correct on self-build
       ansible.builtin.file:
         path: "{{ matrix_synapse_usage_exporter_docker_src_files_path }}"
@@ -64,10 +60,6 @@
         force: "yes"
       become: true
       become_user: "{{ matrix_user_name }}"
-      environment:
-        GIT_CONFIG_COUNT: "1"
-        GIT_CONFIG_KEY_0: safe.directory
-        GIT_CONFIG_VALUE_0: "{{ matrix_synapse_usage_exporter_docker_src_files_path }}"
       register: matrix_synapse_usage_exporter_git_pull_results
 
     - name: Check if synapse-usage-exporter Docker image exists