Review Mozilla 1948636: Change query parameter handling in EngineURL to be consistent, regardless of how the full URL is specified

🔍 Bugzilla Audit

Bugzilla: https://bugzilla.mozilla.org/show_bug.cgi?id=1948636

Commit: 8f0c55f2

Description

Changes made in this bug directly conflict with the changes we make to the EngineURL.getSubmission function in toolkit/components/search/SearchEngine.sys.mjs in commit "BB 40925: Implemented the Security Level component". The conflicts were resolved in the rebase of 138, but we need to check functionality is intact.

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