Add ATLAS_CHECK_THREAD_SAFETY to three InnerDetector packages

• In order to confirm and keep thread safety of the following three packages, ATLAS_CHECK_THREAD_SAFETY files were added.
  • TRT_ConditionsData
  • TRTMonitoringRun3
  • FastSiDigitization
• Some changes were necessary
  • Remove static from methods
  • Change static const char* to static const std::string to be thread safe
  • Add const to return values of const methods
  • Remove unused mutable variable
  • Remove unnecessary mutable keyword
  • Remove static variable
• To follow the ATLAS coding standard
  • Use dynamic_cast
• Outputs should not be changed.
• No JIRA ticket