Do not notify SS change with invalid subId

(This is a reupload of ag/8541406.)

If a service state change is reported as a subscription is becoming
invalid (i.e. no longer connected to a phone), the current behavior can
sometimes notify this change to all PhoneStateListeners regardless of
which subId they registered to listen on (namely this happens when the
subscription was attached to the default phone).

This change removes that behavior so that no listeners are notified if
the subscription is invalid.

Test: manually verified on DSDS that when
  1. erasing eSIM when it is default and
  2. removing pSIM when it is default,
  the service state triangle for the other SIM is unaffected
  Also made sure that signal strength is rebroadcast when sub becomes
  valid, so b/138357571 did not show up 5/5 times
Bug: 133140128
Change-Id: I2ba6a971fff4e29ccd2166c381308fcd953f5bc0
Merged-In: I2ba6a971fff4e29ccd2166c381308fcd953f5bc0