remove immutable checks, plus import cleanup, plus test refactor

[Shalucik]

Description

• removed immutable label check for subresources, to prevent conflicts with external mutators
• cleaned imports
• removed functions that had been moved to the Smooth-Operator library
• refactor test to avoid race issues with creating/deleting resources from testenv
• add local dev env file
• replaced pointer functions with go 1.26 new()

Type of change

(Remove irrelevant options)

• Minor change (typo, formatting, version bump)
• New feature
• Improvement of existing feature
• Bugfix
• Refactoring
• Configuration change
• Breaking change

Checklist:

• I've double-checked the code in this PR myself
• I've left the code better than before (boy scout rule)
• The code is readable, comments are added that explain hard or non-obvious parts.
• I've expanded/improved the (unit) tests, when applicable
• I've run (unit) tests that prove my solution works
• There's no sensitive information like credentials in my PR