Fix ValidationValidator not to accept terminating newline

[zonuexe]

I've seen #45769 merged and realize that these methods are probably accept unintended newlines.

The manual (PHP: Meta-characters) says that $ matches not only the end of the string, but also the terminating newline.
The \A and \z pairs are safe because they always match leading and trailing ends regardless of mode.

PHP: Escape sequences - Manual

The \A, \Z, and \z assertions differ from the traditional circumflex and dollar (described in anchors ) in that they only ever match at the very start and end of the subject string, whatever options are set. They are not affected by the PCRE_MULTILINE or PCRE_DOLLAR_ENDONLY options. The difference between \Z and \z is that \Z matches before a newline that is the last character of the string as well as at the end of the string, whereas \z matches only at the end.

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I'm not a Laravel user, so I'm not too concerned with this issue. If more work is needed for compatibility, please close this PR and have someone else work on it again. thank you!