Fix: Boot time regression on systemRunning

After lifecycle refactoring for IMS, systemRunning is under
ActivityManager ready phase. Need to move complex operations, out of
the boot phase. Alternatively can selectively fix all the operations
in IMS.systemRunning() so that they don't take any significant time.
As a stop gap shifting all of system running to handler thread.

Bug: 380801853
Test: manual on ABTD
Flag: EXEMPT bugfix
Change-Id: I915ab231af980cd5dee72e030dd819659ab99b74