RFR: 8290180: Convert com/sun/management/UnixOperatingSystemMXBean/GetOpenFileDescriptorCount.sh to jtreg java version [v2]

[Leonid Mesnik]

On Thu, 14 Jul 2022 22:46:09 GMT, Bill Huang <duke at openjdk.org> wrote:

>> This is a task to convert shell tests to Java tests. The shell scripts to be removed are responsible for compiling Java files and running the tests on Linux systems. This functionality can be achieved with JTReg tag @requires (os.family=="linux").
>
> Bill Huang has updated the pull request incrementally with one additional commit since the last revision:
> 
>   Removed othervm option and fixed @requires coding style.

The variables should use camelCase. Like min_count_for_pass -> minCountForPass 
Variable trace not needed, just print count always
The mention of Solaris should be removed from comments, also I don't know if instructions for manual testing are needed, but it would be better to say "to know actual value run smth".

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PR: https://git.openjdk.org/jdk/pull/9503