Fix password validator failure

What does this MR do and why?

Fix https://jihulab.com/gitlab-cn/gitlab/-/jobs/5232711, the submit button may be a button element, remove the input selector to make the selector more general

Screenshots or screen recordings

How to set up and validate locally

1. Set up gitlab in EE premium plan at least
2. go to http://{YOUR_HOST}/admin/application_settings/general and expand Sign up restrictions and turn on password complexity
3. go to http://127.0.0.1:3000/admin/users edit any user, fill the password input with aA
4. submit the form

MR acceptance checklist

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• I have evaluated the MR acceptance checklist for this MR.