libtracker-bus: Reduce D-Bus proxy initialization time
libtracker-bus: Reduce D-Bus proxy initialization time

We do not use properties or signals with these proxies. This change
avoids unnecessary D-Bus calls at initialization time to load
properties and connect to signals.

hoheinzollern/tracker,outofbits/tracker,hoheinzollern/tracker,hoheinzollern/tracker,outofbits/tracker,outofbits/tracker,hoheinzollern/tracker,hoheinzollern/tracker,outofbits/tracker,hoheinzollern/tracker,outofbits/tracker,outofbits/tracker,outofbits/tracker,hoheinzollern/tracker