test() - Added comprehensive unit tests for util/executables.go file

[Alokxk]

Description

This PR introduces a comprehensive unit test suite for the command execution functions within the util package.

To ensure tests are fast, reliable & isolated from the host environment, a mocking strategy (TestHelperProcess) is used. This avoids the need for any external command-line tools to be installed.

How Has This Been Tested?

Local Testing:

go test ./util -v
go test ./util -cover

Overall Coverage Increase: This PR increases the overall coverage by 1.5%

Checklist:

• The title of the PR states what changed and the related issues number (used for the release note).
• Does this PR requires documentation updates?
• I've updated documentation as required by this PR.
• I have performed a self-review of my own code.
• I have commented my code, particularly in hard-to-understand areas.
• I have tested it for all user roles.
• I have added all the required unit test cases.

Does this PR introduce a breaking change?