Remove sylinked git cache functionality

Prior to zuul v3 there was a cache of all git repositories
on the host, and this functionality used a bind-mount and
symlinks to pull the cache into the repo server as a way
to cut time taken and reduce errors due to git cloning.

The cache is no longer there, so the functionality which
implements the symlink and bind-mount is being removed.

The ability to make use of a git cache is still available,
but the cache will be synchronised into the container
instead of using bind mounts and symlinks.

This cuts down the complexity of the implementation.

Change-Id: I397c67a4b0166ad9f42a186f5c7137571772693a
Depends-On: Id95ad2f01b52222a07cb0775026d941ab86cd9ab

tasks/repo_pre_install.yml

@@ -51,6 +51,7 @@
     group: "{{ repo_service_group_name }}"
     mode: "{{ item.mode | default('02755') }}"
   with_items:
+    - path: "{{ repo_git_cache_dir }}"
     - path: "{{ repo_service_home_folder }}"
     - path: "{{ repo_service_home_folder }}/.ssh"
       mode: "02700"
@@ -71,19 +72,6 @@
     owner: "root"
     group: "root"
 
-- name: Check if the git folder exists already
-  stat:
-    path: "{{ repo_git_cache_dir }}"
-  register: _git_folder
-
-- name: Git service data folder setup
-  file:
-    path: "{{ (_git_folder.stat.exists and _git_folder.stat.islnk) | ternary(_git_folder.stat.lnk_source, repo_git_cache_dir) }}"
-    state: "directory"
-    owner: "{{ repo_service_user_name }}"
-    group: "{{ repo_service_group_name }}"
-    recurse: true
-
 - name: File and directory setup (root user)
   file:
     path: "{{ item.path }}"