Bug 1782783 - disable browser_test_focus_urlbar.js on linux for frequent failures. patch re-made to solve landing conflicts r=aryx

Differential Revision: https://phabricator.services.mozilla.com/D169883

accessible/tests/browser/events/browser.ini

@@ -23,6 +23,7 @@ skip-if =
 skip-if =
   os == 'win' && os_version == '10.0' # Bug 1492259
   os == "win" && os_version == "6.1" # Skip on Azure - frequent failure
+  os == "linux" # Bug 1782783
 [browser_test_A11yUtils_announce.js]
 [browser_test_selection_urlbar.js]
 skip-if =