Merge pull request #25513 from julienw/move-sticky-header-out-of-launch-...

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Bug 1089145 - [Messages] Move the sticky header init out of the critical...
(cherry picked from commit 0fe329342ee4559c58cd271b0c19b49be88943b8)

Conflicts:
	apps/sms/js/thread_list_ui.js
	apps/sms/test/unit/thread_list_ui_test.js
	shared/js/sticky_header.js