Convert trash modal unit tests to Vue Testing Library (learningequality#5816)

* test: Made changes to trashModal test file to use vue testing library

* Updated the test file

* Updated test file again

* Added necessary stubs

* Finalizing

* Updated test file

* Updated test file

* Refined testcases

* Updated the test based on reviwer feedback

* replaced getbytestid wiht getbyrole

* Reviewed needed chnages

* Reviewed needed chnages

Author: Prashant-thakur77