policy: Remove unused includes and DEPS from user_cloud_policy_store* .

BUG=271392

Review URL: https://codereview.chromium.org/72593002

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@235130 0039d316-1c4b-4281-b951-d872f2087c98
SVN changes up to revision 235130