[Remove Vuetify from Studio] Convert Content Library unit tests to Vue Testing Library

[vtushar06]

Summary

Converted Content Library Catalog List tests from Vue Test Utils to Vue Testing Library per issue #5527.

Changes:

• Replaced mount() with render(), screen, and userEvent
• Created mock store/router factories for isolated testing
• Stubbed child components and mocked translations
• Focused on user-observable workflows: catalog loading, search/filtering, selection mode, and download UI

Test coverage:

Converted from 17 tests to 9 tests following VTL philosophy
All major user workflows maintained
Removed tests for internal state (excluded array, component methods) that aren't user-visible

Verification:

Ran npm test -- catalogList.spec.js

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References

Closes: #5527

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Reviewer guidance

To test: npm test -- catalogList.spec.js
And Also focus that Tests uses VTL Pattern (not internal state access) and all critical workflow are still covered i.e load,search,select,download
Due to this test count reduced
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Review focus:

Tests use VTL patterns (not internal state access)
All critical workflows covered (load, search, select, download)
Note: Test count reduced because VTL tests behavior, not implementation details

[MisRob]

Thank you @vtushar06, within next two weeks, we will assign a reviewer.