NetworkController: Remove `setActive` option from `upsertNetworkConfiguration`

[mcmire]

There are too many methods that can be used to switch networks, and as a result we have a LOT of tests for NetworkController. It is not difficult for consumers to call setActiveNetwork after calling upsertNetworkConfiguration if they wish to switch to a newly added or updated network. Therefore to minimize the test suite, we should remove this option from upsertNetworkConfiguration.