style: Fix superfluous-else rules for raise, continue and break (RET506, RET507, RET508)

[echoix]

Following #4459, where when there was an if with a return, the next elif: or else: could be flattened with one less nested level, this PR addresses three similar rules, where instead of having return, there is RET506 for a raise, RET507 for continue in a loop, and RET508 for a break in a loop.

There are only 35 changes files, and quite simple, but in a couple of files, there was a lot of nested conditions/long nested conditions that became flattened and got reformatted with fewer lines. So the line change count is bigger than it appears.

[echoix]

I'm not 100% sure that there won't be conflicts with my other open PRs. Please take a look at the others that are already ready before this one.