Merge #2732

2732: Only account for distinct attempts in rate limits r=mergify[bot] a=nextgens

## What type of PR?

enhancement

## What does this PR do?

Only account for distinct attempts in rate limits. This is solving the problem related to users changing their passwords and having their client hammer the old credentials.

Reduce the default to 50 distinct passwords per day

### Related issue(s)

## Prerequisites
Before we can consider review and merge, please make sure the following list is done and checked.
If an entry in not applicable, you can check it or remove it from the list.

- [x] In case of feature or enhancement: documentation updated accordingly
- [x] Unless it's docs or a minor change: add [changelog](https://mailu.io/master/contributors/workflow.html#changelog) entry file.


Co-authored-by: Florent Daigniere <nextgens@freenetproject.org>
Co-authored-by: Florent Daigniere <nextgens@users.noreply.github.com>

setup/templates/steps/config.html

@@ -47,7 +47,7 @@ Or in plain english: if receivers start to classify your mail as spam, this post
   <label>Authentication rate limit per user</label>
   <!--   Validates number input only -->
   <p><input class="form-control" style="width: 9%; display: inline;" type="number" name="auth_ratelimit_user"
-  		value="100" required > / day
+  		value="50" required > / day
   </p>
 </div>