git: openjdk/loom: fibers: Drop thread groupsing from jcmd Thread.vthread_summary output

[duke]

Changeset: 6117d300
Branch: fibers
Author:    Alan Bateman <alan.bateman at oracle.com>
Date:      2024-11-21 16:40:33 +0000
URL:       https://git.openjdk.org/loom/commit/6117d3003749ecab857683a31c1283b11d15903f

Drop thread groupsing from jcmd Thread.vthread_summary output

! src/java.base/share/classes/jdk/internal/vm/VThreadSummary.java
! src/jdk.jcmd/share/man/jcmd.md
! test/hotspot/jtreg/serviceability/dcmd/thread/VThreadSummaryTest.java