Fix logs in ActivityTestJunit4

Trim strings captured from shell command output in
disableScreenOffAndSleepTimeouts(). Remove the final newline and ensures
that the matching logs are correctly formatted.

Use more accurate function names in logFeatureFlags().

Bug: 434079881
Test: atest DocumentsUIGoogleTests:FilesActivityUiTest#testClickRecentM3
Flag: EXEMPT fixing logs in tests
Change-Id: Idd4facbd2c401c3509f12b2596d1adfd02316775

Change-Id: I1b2c57c66ab75caad5c57840c67f7eb8c49bec8d