Fix cosmetic problems in YAML source

This change corrects problems reported by the `yamllint` linter.

Since key duplication problems were removed in 4d48711, this commit
mainly fixes trailing spaces and extra empty lines at beginning/end of
files.

test/integration/targets/apt_repository/tasks/cleanup.yml

@@ -15,4 +15,3 @@
 - name: remove ppa key
   apt_key: id={{test_ppa_key}} state=absent
   ignore_errors: true
-

test/integration/targets/apt_repository/tasks/main.yml

@@ -18,4 +18,3 @@
 
 - include: 'apt.yml'
   when: ansible_distribution in ('Ubuntu')
-