8164523: Clean up metadata for event based tracing
Reviewed-by: mlarsson, mgronlun

Merge

8149023: Event based tracing should cover safepoint begin and end
Summary: Add events to safepoint begin and end
Reviewed-by: dholmes, mgronlun, egahlin

8151653: Hotspot build does not respect --enable-openjdk-only
Reviewed-by: tbell, dholmes