Enable continuous testing for Battery Saver code.

Enabling pre- and post-submit tests for Battery Saver so we can catch
regressions faster.

Also tag flaky tests.

Bug: 146454935
Test: Navigate to directory and run `atest`
Change-Id: I34cc570f738461b4e6d9736aea25c0d31f6b5f0c
3 files changed