Change variables to atomic variables.

The following variables are updated in this cl:
- mDemoTimeoutDuration
- mIsEmergencyCommunicationEstablished
- mSendingInProgress

Bug: 409610090
Test: atest
Flag: com.android.internal.telephony.flags.satellite_improve_multi_thread_design
Change-Id: I32b406982710eae447a5141fad02ba62273395d8