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

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https://hg.mozilla.org/integration/gaia-central/rev/7849a5c8e80c
Author: steveck-chung <schung@mozilla.com>
Desc: Merge pull request #14596 from steveck-chung/DSDS-sim_switch_for_MMS

Bug 949326 - [DSDS][MMS] Switching data call follow-up fixing for default service ID type changes, r=julienw

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https://hg.mozilla.org/integration/gaia-central/rev/08e6e42168f8
Author: Steve Chung <schung@mozilla.com>
Desc: Bug 949326 - [DSDS][MMS] Switching data call follow-up fixing for default service ID type changes