Correct git config item name in mirror-workspace-git-repos

It appears this setting inadvertently had an extra word "ignore"
included in the key name, and later versions of the git module in
Ansible (5) throw an error in that case.  Remove it so that this
role will work in all versions.

This has been previously tested in a base-test cycle via
test-mirror-workspace-git-repos.

Change-Id: I597aa8d331e53955e826f09aa51a579e12c94f85

roles/mirror-workspace-git-repos/tasks/main.yaml

@@ -1,6 +1,6 @@
 - name: Allow pushing to non-bare repo
   git_config:
-    name: receive.denyCurrentBranch ignore
+    name: receive.denyCurrentBranch
     value: ignore
     scope: local
     repo: "{{ ansible_user_dir }}/{{ zj_project.value.src_dir }}"