git: openjdk/loom: fibers: Undo some vthread wrapper code that was added long ago and is causing some test failures.

[duke]

Changeset: 873eb941
Author:    Chris Plummer <chris.plummer at oracle.com>
Date:      2021-09-02 18:14:43 +0000
URL:       https://git.openjdk.java.net/loom/commit/873eb9416f756e9ee4fdfefc756fd576ba4156cf

Undo some vthread wrapper code that was added long ago and is causing some test failures.

! test/hotspot/jtreg/vmTestbase/nsk/share/jdi/JDIBase.java