Reset arguments after emitting a perfetto event

We were always resetting arguments but this was left to the caller
and was one more non-trivial JNI call. While we are in the library
code we should just reset the arguments right away

Test: atest PerfettoTraceTest
Bug: 303199244
Flag: android.os.perfetto_sdk_tracing_v2
Change-Id: If093c436c24b5519a98d19f7ccf7171f1ded3793