RFR: JDK-8325496: Make TrimNativeHeapInterval a product switch [v5]

[Thomas Stuefe]

> [JDK-8293114](https://bugs.openjdk.org/browse/JDK-8293114) introduced automatic C-heap trimming, for now supported only by the glibc. It is controlled by the command line switch `TrimNativeHeapInterval`. The feature has proven very valuable to customers, and all issues have been ironed out. So, I'd like to make this switch a non-experimental product switch.

Thomas Stuefe has updated the pull request incrementally with two additional commits since the last revision:

 - Update TestTrimNative.java
 - Update NativeHeapTrimmerGtest.java

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Changes:
  - all: https://git.openjdk.org/jdk/pull/17799/files
  - new: https://git.openjdk.org/jdk/pull/17799/files/912df1b2..116df05d

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jdk&pr=17799&range=04
 - incr: https://webrevs.openjdk.org/?repo=jdk&pr=17799&range=03-04

  Stats: 4 lines in 2 files changed: 0 ins; 0 del; 4 mod
  Patch: https://git.openjdk.org/jdk/pull/17799.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/17799/head:pull/17799

PR: https://git.openjdk.org/jdk/pull/17799