Send readme parameter when creating projects

The web page from which this call is taken has a readme selector
and a default value of "Default" that we're not sending in this
request. Send it to avoid gitea not being able to find the empty
readme.

Also, add gitea-git-repos to the files section of system-config-run-gitea
so that we actually test it.

Change-Id: Ieec94aadb63fa097f10a3f325dd105b30e610dd9

.zuul.yaml

@@ -539,6 +539,7 @@
       - playbooks/zuul/templates/group_vars/gitea.yaml.j2
       - playbooks/zuul/templates/group_vars/gitea-lb.yaml.j2
       - playbooks/roles/gitea/
+      - playbooks/roles/gitea-git-repos/
       - playbooks/roles/haproxy/
       - testinfra/test_gitea.py
       - testinfra/test_gitea_lb.py

playbooks/roles/gitea-git-repos/tasks/setup-repo.yaml

@@ -21,6 +21,7 @@
       description: "{{ (project.description | default(''))[:255] }}"
       name: "{{ repo }}"
       private: false
+      readme: Default
   register: create_repo_result
 - name: Adjust repo settings
   when: gitea_always_update or project.project not in gitea_repos