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

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https://hg.mozilla.org/integration/gaia-central/rev/cf8f5a0d86b9
Author: gitmai <mri@tid.es>
Desc: Merge pull request #15294 from gitmai/bug-959543-remove-lastSim-property

Bug 959543 - [CostControl] Remove reference to lastSIM property
r=salva

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https://hg.mozilla.org/integration/gaia-central/rev/56eab7891f68
Author: mai <mri@tid.es>
Desc: Bug 959543 - [CostControl] Remove reference to lastSIM property
Bumping manifests a=b2g-bump