Dont reuse sessions from before_hooks

What does this MR do?

Attempt at fix for #196770 (closed)

Instead of sharing the session between before_hooks and tests, let's use separate sessions against the same instance.

Does this MR meet the acceptance criteria?

Conformity

• [-] Changelog entry
• [-] Documentation (if required)
• Code review guidelines
• Merge request performance guidelines
• Style guides
• [-] Database guides
• [-] Separation of EE specific content