Update existing prefs for ESR78
A few of our existing prefs have been removed or renamed.
Remove:
- browser.cache.frecency_experiment (removed in https://bugzilla.mozilla.org/show_bug.cgi?id=1573887)
- browser.casting.enabled (removed in https://bugzilla.mozilla.org/show_bug.cgi?id=1393582)
- device.camera.enabled (removed in https://bugzilla.mozilla.org/show_bug.cgi?id=1408957)
- general.useragent.updates.enabled (removed in https://bugzilla.mozilla.org/show_bug.cgi?id=1513574)
- general.useragent.updates.url (removed in https://bugzilla.mozilla.org/show_bug.cgi?id=1513574)
- services.blocklist.update_enabled (removed in https://bugzilla.mozilla.org/show_bug.cgi?id=1458917)
- experiments.enabled (removed in https://bugzilla.mozilla.org/show_bug.cgi?id=1420908)
- browser.syncPromoViewsLeftMap (removed in https://bugzilla.mozilla.org/show_bug.cgi?id=1279224)
Rename:
- geo.wifi.uri --> geo.provider.network.url (renamed in https://bugzilla.mozilla.org/show_bug.cgi?id=1613627)