Enable extra error_prone rule against JUnit4 usage in JUnit3

Add rule against CTS harness to prevent using JUnit4
concepts inside JUnit3 (which would not work very well).
And fix one occurence of it.

Test: build
./cts-tradefed run cts-dev -m CtsDeviceIdleHostTestCases
Bug: 72663865

Change-Id: I4d38e6f17e9393b7af3463800dac546c8cf79e74
2 files changed