I've added a setting so you can get back to the previous behavior in the next fix release, v25.0.2.
Once that is released, you'll need to go into the formatting settings for C/C++, and under Indent -> Indent Rule Exceptions turn "Indent leading initializer colon" "off". Then editing will work like before, where
1) hitting ":" won't shift your indent out
2) hitting return after an initializer will put you in the same column the ":" was put in, instead of indenting in.