Fix errors caught by aapt2

Fixes:
frameworks/base/tests/ActivityTests/res/values/themes.xml:18: error: resource previously defined here.
frameworks/base/tests/ActivityTests/res/values/themes.xml:21: error: duplicate value for resource 'style/SlowDialog' with config ''.

Bug: 79481102
Test: m java FORCE_AAPT2=true
Change-Id: I06b1552220b5acd8790d72555e36a0466c523b67