Improve password reset email formatting #19357

Description:

Fixes #19354

Quick fix for plain text and HTML password reset emails.

A non-HTML body is now added to the email so the link is properly displayed for plain text email clients.
The HTML body paragraph element containing the link now has inline styling added to prevent the reset link overflowing off the screen/page.

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

@bx80 some tests had been failing due to the last change (as they try to grep the token from the email content). I've pushed a simple fix for that.