Is your feature request related to a problem? Please describe.
After I added persist to most of the methods, we have a problem with potential memory leaks during tests because a lot of data is not unpersisted.

Describe the solution you would like
Explicitly unpersist results in tests.

Component

• Scala Core Internal
• Scala API
• Spark Connect Plugin
• Infrastructure
• PySpark Classic
• PySpark Connect

Additional context

Are you planning on creating a PR?

• I'm willing to make a pull-request