fix: Clarified Variable Reference Update unixStartScript.txt

[annwag]

PR Description

I noticed a small but potentially confusing redundancy in the startup script. Specifically, the JAVA_OPTS variable is mentioned twice in the following comment:

#   * DEFAULT_JVM_OPTS, JAVA_OPTS, JAVA_OPTS, and optsEnvironmentVar are not allowed to contain shell fragments,  

This duplicate mention doesn't add value and could lead to misinterpretation. I've adjusted the line to ensure clarity:

#   * DEFAULT_JVM_OPTS, JAVA_OPTS, and optsEnvironmentVar are not allowed to contain shell fragments,  

This update simplifies the comment and aligns it with the intended meaning.
No functional changes were made; this is purely a documentation improvement to enhance readability and reduce ambiguity.

Documentation

• I thought about documentation and added the doc-change-required label to this PR if updates are required.

Changelog

• I thought about adding a changelog entry, and added one if I deemed necessary.

[tbenr]

against contribution guidelines. closing.