Clean up usage of internal classes and utils in widget CTS tests

Some remaining uses of android.R.styleable and tests that depend heavily
on private APIs prevent this CL from fully moving LOCAL_SDK_VERSION to
current, but those will be addressed later by either API changes or
removal of the offending tests.

Bug: 13281485
Change-Id: Iff4253302aba4bff12eebb501537b12dfbda1467
11 files changed