Remove unused gradle properties & migrate tests to Junit5

[abelsromero]

Pure boring maintenance:

• Removed unused properties in gradle
• Migrated test to Junit5
• Refactor tests to improve readability (opinionated 😅 )

[abelsromero]

Btw, I removed the delete of outputs from tests since all tests generate outputs in build. Doesn't seem to add much with the scope of the project (not like we generate teras of data).

[robertpanzer]

Thank you! That's great!