Fix intermittent category select flake in category_scopes_spec for issue

[narendrapatel00]

fixes #6726

Fixes an intermittent failure in category_scopes_spec.rb by stabilizing async select interactions for category and template selection.

What changed

• Added a shared helper choose_select_option(selector, search_text, option_text, exact_text: false) in category_scopes_spec.rb
• Replaced fragile direct find(:css, ...).click calls with the helper across category/template selection flows
• Helper waits for the async dropdown option to appear before clicking, reducing timing-related flakiness

Why

The existing spec was vulnerable to race conditions when React/AsyncSelect options were not yet rendered
This change makes the test more reliable without changing application behavior