client: Fix Remote Cores marked unsaved on load

Fix Remote Cores (CoreAccountSettingsPage) wrongly being marked as
unsaved when loading if a default core account was chosen and the
index in the QComboBox was not 0.

This likely happened due to the change of setCurrentIndex on
autoConnectAccount triggering the state as changed, due to a missing
call to setChangedState().  Possibly.

Also clean up if statement scopes while we're here.

Test case:
> Add two accounts, "A" and "B"
> Pick "B" as default account
> Save, close Settings dialog, re-open
> Select Remote Cores, note that it's treated as if changes were there