[power-throttling] Remove log and change variable name

This is a superficial change where we
1. delete a log spamming watch devices when power-throttling config is not present.
2. Change name of customAnimationRateSec to customAnimationRate as the rate is not in seconds

Flag: EXEMPT log only update
Bug: 369304377
Test: n/a only logging changes.

Change-Id: I18c063c8f48f0e99450c8406f566a2bc30b7c499