Drop browser.urlbar.update2.engineAliasRefresh

🔍 Bugzilla Audit

• Bugzilla: https://bugzilla.mozilla.org/show_bug.cgi?id=1995002
• Commit: 5f2e0bd9

Description

We had:

// tor-browser#44262: Disable adding search engines from HTML forms
pref("browser.urlbar.update2.engineAliasRefresh", false);

too bad that pref has been removed in the aforementioned commit.

But at least the bug says this has been fully removed, so let's removed the pref.

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