Configure sepolicy for TracingServiceProxy

Configures sepolicy to allow for the new TracingServiceProxy system
services, and to allow Perfetto to access the service.

Bug: 175591887
Test: Validated the service started successfullyy, and invoked via CLI
Change-Id: Idb6438948a9d96063f8455544b97ef66267cde23
diff --git a/private/service_contexts b/private/service_contexts
index 5369b54..dc6985d 100644
--- a/private/service_contexts
+++ b/private/service_contexts
@@ -259,6 +259,7 @@
 time_zone_detector                        u:object_r:timezonedetector_service:s0
 timezone                                  u:object_r:timezone_service:s0
 thermalservice                            u:object_r:thermal_service:s0
+tracing.proxy                             u:object_r:tracingproxy_service:s0
 transformer                               u:object_r:transformer_service:s0
 trust                                     u:object_r:trust_service:s0
 tv_input                                  u:object_r:tv_input_service:s0