Change variables to atomic variables

The following variables are updated in this cl:
- mTimeoutMillis
- mOemEnabledTimeoutMillis
- mIsTimerTimedOut
- mCountOfTimerStarted
- mIsTestEmergencyNumber

Bug: 410859840
Test: atest
Flag: com.android.internal.telephony.flags.satellite_improve_multi_thread_design
Change-Id: Icf9f725eb5a57e7f68218ae6caca045b409a42a8