Apply AppModeFull to BrightnessTest class

BrightnessTest case causes failure for CTS
Instant due to permission issue.

Add AppModefull to BrightnessTest class which
will exclude all tests in it.

This change is suggested by google.

Test: run cts -m CtsDisplayTestCases
--module-parameter INSTANT_APP
Bug: 174211654
Change-Id: I41092ae8092417bf848098d767717cf2b2ca6c56
1 file changed