RFR: 8328234: Remove unused nativeUtils files

[Leonid Mesnik]

A couple of files
open/test/hotspot/jtreg/vmTestbase/nsk/share/NativeUtils.java
open/test/hotspot/jtreg/vmTestbase/nsk/share/native/native_utils.cpp

are not used and could removed.
Tesed with tier1 and all vmtestbase tests. Also grepped all sources to find usages.

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Commit messages:
 - 8328234: Remove unused nativeUtils files

Changes: https://git.openjdk.org/jdk/pull/18318/files
  Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=18318&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8328234
  Stats: 74 lines in 2 files changed: 0 ins; 74 del; 0 mod
  Patch: https://git.openjdk.org/jdk/pull/18318.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/18318/head:pull/18318

PR: https://git.openjdk.org/jdk/pull/18318