test: Drop 'OO.ui' file prefix in test suites

* Remove "oo." file prefix (matching the src directory).
* Remove redundant comments.
* Drop "OO." prefix from QUnit module names, so that the
  test module names match the logical build components of the
  library itself.

See also I9230ba0cd8f4efad in oojs/core.

Change-Id: Iba4a02562976aff5d8cdc4a55ea58ab153ebe168