Create user submit button continuously in a loading state after catching an error

During creating a new user, if we catch an error, the submit button continuously has disabled and loading state. User has to reload page and try to create user again

## Expected Behavior
After catching an error, the user can make some changes and click the submit button again

## Current Behavior
Submitting is blocked, so the user has to reload the page to try to create a new user again

## Possible Solution

## Steps to Reproduce (for bugs)

1. Open the Create New User page
2. Add some user data which can cause an error. For example, you can add an already existing `Username`
3. Click on the submit button.
4. Observe the create user submit button
5. The button has a loading state even after changing the username field
## Context

## Your Environment

* Graylog Version: 6.2
* Java Version:
* OpenSearch Version:
* MongoDB Version:
* Operating System:
* Browser version: