Bumping gaia.json for 2 gaia revision(s) a=gaia-bump

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https://hg.mozilla.org/integration/gaia-1_4/rev/c512f9a84806
Author: Andrew Sutherland <asutherland@asutherland.org>
Desc: Merge pull request #19000 from asutherland/email-size-limit-fix

[Tarako][Email][LMK] Email attachment size limit logic bug results in too-large attachments being attached than detached rather than never detached. Results in email app getting killed. r=mcav

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https://hg.mozilla.org/integration/gaia-1_4/rev/6a176d035384
Author: Julien Wajsberg <felash@gmail.com>
Desc: Merge pull request #18233 from julienw/995173-fix-notice-timeout-v2

Bug 995173 - [Messages] The in-app notification for the "message is too ...
Conflicts:
	apps/sms/js/thread_ui.js
Bumping manifests a=b2g-bump