Bumping gaia.json for 4 gaia-central revision(s) a=gaia-bump

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https://hg.mozilla.org/integration/gaia-central/rev/005338cf9284
Author: EragonJ <eragonj@eragonj.me>
Desc: Merge pull request #12572 from EragonJ/bug-920445

Bug 920445 - [Flatfish][homescreen] fix search_page enabled customizatio...

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https://hg.mozilla.org/integration/gaia-central/rev/7063c925fcc7
Author: EragonJ <eragonj@eragonj.me>
Desc: Bug 920445 - [Flatfish][homescreen] fix search_page enabled customization

- remove unused dom elements
- update test
- update tablet customization settings

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https://hg.mozilla.org/integration/gaia-central/rev/69d3a2c5995e
Author: vingtetun <21@vingtetun.org>
Desc: Merge pull request #12830 from vingtetun/lazyload.no.in.apps.startup

Bug 920561 - Ensure LazyLoader.load does not slow down app rendering. r=...

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https://hg.mozilla.org/integration/gaia-central/rev/218e69c04d0d
Author: Vivien Nicolas <21@vingtetun.org>
Desc: Bug 920561 - Ensure LazyLoader.load does not slow down app rendering. r=etienne,kaze