tombstoned: Improve message on java trace completion.

For java traces, log the kind of dump as well as the PID of the
completed dump. This makes it easier to correlate dump requests with the
actual file they're written to.

Sample log statement:
E /system/bin/tombstoned: Traces for pid 4737 written to: /data/anr/trace_00

The message for native traces / tombstones remains unchanged because
several tools parse it.

Test: manual
Bug: 32064548

Change-Id: I7b3792dd5ae312ee0bc055c22ec3f7c747152072