Make system_server atrace category work with traced_probes

Historically most uses of atrace happen via the shell domain.

There are two exceptions:
- boot tracing
- traced_probes

We need to get feature parity, so atrace has the same behavior
when is invoked either via shell or from its own domain (e.g.
via traced_probes that has an auto_trans rule into atrace on exec).
Atrace works by setting system properties to enable tracing from userspace
then poking all the binder services to read the system properties (see [1]) so
enabling the system_server category requires the ability to call binder
methods on the system_server.

For more use cases see b/113127224

[1]: https://android.googlesource.com/platform/frameworks/native/+/9ead54bed65d486fe435793cbe98ed8b4786f7be/cmds/atrace/atrace.cpp#545

Bug: 113127224
Test: Add an atrace category to the Perfetto config and confirm the data
shows up.

Cherry-picked from aosp/747608

Change-Id: Id077eff960ffb1cdd7b0ce84b21ac9ef70444a4a
Merged-In: Id077eff960ffb1cdd7b0ce84b21ac9ef70444a4a