Rate limit battery external stats collection in takeUidSnapshot(s).

Bug: 74146897
Test: atest cts/tests/tests/os/src/android/os/health/cts/SystemHealthManagerTest.java
Test: atest core/tests/coretests/src/com/android/internal/os/BatteryStatsTests.java
Change-Id: I2e01146718c3ce65d230308097622b958cb2897a