Stop calling binder.linkToDeath in ServiceConnector.

Since `binderDied()` callback is same signal as service crashing, and prior implementation ultimately either invokes `unbind()` due to `binderDied()` following a `onServiceDisconnected` or vice-versa.
It is more straightforward to call `unbind()` regardless, whenever `onServiceDisconnected` invoked, so this cleans up resources, allows rebinding upon receiving a client request.

This change removes impl for `onBindingDied` and `binderDied` since we expect to do same behavior in those cases and avoid duplicate calls of `unbind` by not implementing them.

Bug: 418214801
Bug: 424695730
Flag: EXEMPT bugfix
Change-Id: I6d006df08174e6309f5c1e6b1581f457a7e69493