We should not exit in rake task

What does this MR do and why?

We should not exit in rake task.

If we call exit it'll stop any tests running after tests running this specific test.

How to set up and validate locally

Run this to verify:

bin/rspec -f d spec/tasks/gitlab/db_rake_spec.rb spec/lib/forever_spec.rb

• Before: We can observe that with exit it'll not run spec/lib/forever_spec.rb.
• After: With next the last test it run is spec/lib/forever_spec.rb.

MR acceptance checklist

This checklist encourages us to confirm any changes have been analyzed to reduce risks in quality, performance, reliability, security, and maintainability.

• I have evaluated the MR acceptance checklist for this MR.

See #349990 (closed)