RFR: 8335625: Update Javadoc for GetCpuLoad [v3]

[Joakim Nordström]

> Can I get a review of this documentation update to clarify the usage of GetCpuLoad (and inherently deprecated GetSystemCpuLoad) and GetProcessCpuLoad.
> 
> Calling either of these methods in quick succession can lead to unrepresentative results due to too few data points.
> 
> This behavior is easy to reproduce on at least Linux (Windows implementation enforces a 500 ticks duration); when calling GetCpuLoad repeatedly CPU load values of either 0, 0.5, or 1 will be returned.
> 
> double cpuLoad1 = getCpuLoad();
> double cpuLoad2 = getCpuLoad();   // not enough ticks has passed to give representative values
> 
> Worth noting is that this holds true even if getSystemCpuLoad() is called. 
> 
> double cpuLoad1 = getCpuLoad();
> double cpuLoad2 = getSystemCpuLoad();   // not enough ticks has passed to give representative values, since getSystemCpuLoad effectively calls getCpuLoad.

Joakim Nordström has updated the pull request incrementally with one additional commit since the last revision:

  Added implNote and made some re-arrangements

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Changes:
  - all: https://git.openjdk.org/jdk/pull/20546/files
  - new: https://git.openjdk.org/jdk/pull/20546/files/07b0faa6..af69aa88

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jdk&pr=20546&range=02
 - incr: https://webrevs.openjdk.org/?repo=jdk&pr=20546&range=01-02

  Stats: 51 lines in 1 file changed: 27 ins; 3 del; 21 mod
  Patch: https://git.openjdk.org/jdk/pull/20546.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/20546/head:pull/20546

PR: https://git.openjdk.org/jdk/pull/20546