Revert "Flag WindowManager refresh rate fields for test"

Revert submission 25035744-wmtestflag

Reason for revert: go/android-api-flagging-faq#i-dont-want-to-flag-my-api-can-i-suppress-the-unflaggedapi-lint

Reverted changes: /q/submissionid:25035744-wmtestflag

Change-Id: I1982feb9ec6381dac34f1f6fece1cbb2627f19b3