drive: Handle remove task as a update task.

There can be cases where an updated entry gets deleted later.
Update task and Remove task should be handled by the same code and EntryUpdatePerformer should check if the entry is in trash or not.

Change owner of RemovePerformer to EntryUpdatePerformer.
Rename SyncClient::REMOVE to UPDATE

BUG=260538
TEST=unit_tests
R=kinaba@chromium.org

Review URL: https://codereview.chromium.org/94673002

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@237898 0039d316-1c4b-4281-b951-d872f2087c98
SVN changes up to revision 237898