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

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https://hg.mozilla.org/integration/gaia-1_4/rev/27bfa92d9eaf
Author: David Flanagan <dflanagan@mozilla.com>
Desc: Merge pull request #22375 from davidflanagan/bug1039943-v1.4

Bug 1039943: make gallery exit if it goes to background while scanning o... r=pdahiya a=1.4+

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https://hg.mozilla.org/integration/gaia-1_4/rev/b7bf2d9cf9d8
Author: David Flanagan <dflanagan@mozilla.com>
Desc: Bug 1039943: make gallery exit if it goes to background while scanning on a device with less than 512mb RAM device
(cherry picked from commit bddd3a639ccf6353d06ae215215c4a4ddd31cffa)
Bumping manifests a=b2g-bump