BinderProxy: 'object' vs 'recipient'

Use 'recipient' to refer to memebers of recipient
list and 'object' for IBinder. With both binder
and recipients being referred to as 'objects' it
takes me a long time to read/understand this code.
This has been a longstanding issue.

Bug: 405737267
Test: N/A
Change-Id: I1187324729f3da95210440273723be38552922ac