Remove password when confirmation modal is closed

[michalkleiner]

Description:

As per the title, plus UI tests.

Ref. DEV-12809

Review

• [ ] Functional review done
• [ ] Potential edge cases thought about (behavior of the code with strange input, with strange internal state or possible interactions with other Matomo subsystems)
• [ ] Usability review done (is anything maybe unclear or think about anything that would cause people to reach out to support)
• [ ] Security review done
• [ ] Wording review done
• [ ] Code review done
• [ ] Tests were added if useful/possible
• [ ] Reviewed for breaking changes
• [ ] Developer changelog updated if needed
• [ ] Documentation added if needed
• [ ] Existing documentation updated if needed

[michalkleiner]

@caddoo there was a typo in one of the UI test expected screenshot names, I've corrected that. Can you please re-approve? Ta!