RFR: 8378379: Remove reference to obsolete jdk.net.usePlainSocketImpl property from SSLSocketReset test [v2]

[Jaikiran Pai]

> Can I please get a review of this test-only change which removes the reference to the obsolete `jdk.net.usePlainSocketImpl` property?
> 
> `jdk.net.usePlainSocketImpl` was removed in https://bugs.openjdk.org/browse/JDK-8253119 and plays no role anymore in the JDK. This `test/jdk/sun/security/ssl/SSLSocketImpl/SSLSocketReset.java` test was introduced to reproduce a bug in the implementation of PlainSocketImpl, but doesn't rely on any internal socket implementation details, so I think it should be OK to retain this test and just remove the usage of the property. The property has been playing no role in this test, and the test has been functional, ever since the property was removed in  JDK-8253119.

Jaikiran Pai has updated the pull request with a new target base due to a merge or a rebase. The incremental webrev excludes the unrelated changes brought in by the merge/rebase. The pull request contains four additional commits since the last revision:

 - Sean's review - use othervm
 - merge latest from master branch
 - merge latest from master branch
 - 8378379: Remove reference to obsolete jdk.net.usePlainSocketImpl property from SSLSocketReset test

-------------

Changes:
  - all: https://git.openjdk.org/jdk/pull/29872/files
  - new: https://git.openjdk.org/jdk/pull/29872/files/a06c15a8..d6a8cd8c

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jdk&pr=29872&range=01
 - incr: https://webrevs.openjdk.org/?repo=jdk&pr=29872&range=00-01

  Stats: 18287 lines in 545 files changed: 10110 ins; 3138 del; 5039 mod
  Patch: https://git.openjdk.org/jdk/pull/29872.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/29872/head:pull/29872

PR: https://git.openjdk.org/jdk/pull/29872