Too eager unsaved changes warning when editing native questions (#39157)

* Show unsaved changes warning for native questions only when the query has been changed

* Drop legacyQuery usage

* Add test for new behavior

* Update pathnames for running questions
- required to make native_subquery.cy.spec.js pass - this test suite uses native queries referencing other questions by id instead of a full slug, and upon opening such question the id in the query automatically changes to the full slug, and the URL gets a hash