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/vault/roles/test_vault/tasks/main.yml

@@ -1,4 +1,3 @@
-
 - assert:
     that:
       - 'secret_var == "secret"'

test/integration/targets/vault/roles/test_vault_embedded/tasks/main.yml

@@ -11,4 +11,3 @@
 
 # TODO: add a expected fail here
 # - debug: var=vault_encrypted_one_line_var_with_embedded_template
-