Minor refactorings on Autofill tests:

- Move common code to AbstractAutofillTestCase.
- Copied existing codes to LoginTest, which does not use @Parameters.
- Deprecated AutofillPerfTest (it will be removed once LoginTest has some runs).
- Added some (temporary) no-op tests to help us investigate why some tests are
  missing from the dashboard.

Test: mmma -j ./frameworks/base/apct-tests/perftests/core/ &&  \
  adb install -r $OUT/data/app/CorePerfTests/CorePerfTests.apk && \
  adb shell am instrument -w -e class android.view.autofill.AutofillPerfTest \
  com.android.perftests.core/android.support.test.runner.AndroidJUnitRunner

Bug: 38345816

Change-Id: Iab703205f1e01a1e5413b10c3008aac8efcc5dc2