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/task_ordering/tasks/main.yml

@@ -10,4 +10,3 @@
     that: lookup('file', temppath.stdout) == "one.1.two.1.three.1.four.1.one.2.two.2.three.2.four.2.one.3.two.3.three.3.four.3."
 
 - file: path="{{temppath.stdout}}" state=absent
-