Fix patterns field check when field empty and not required

[Ruud68]

Pull Request for Issue #34102 .

Summary of Changes

validating pattern fails when field is not required and empty, this is not correct. This PR fixes this (in line with J3 validation)
pinging @dgrammatiko

Testing Instructions

see #34102

Actual result BEFORE applying this Pull Request

saving form with empty field is not possible

Expected result AFTER applying this Pull Request

saving form with empty field works correct

Documentation Changes Required

no

[joomdonation]

I think I've started a trend :) :) :)

For JS, we all know that we should ping @dgrammatiko or @Fedik. It's not secret. So no, you are not the one started that trend :D .

[Ruud68]

I hope @dgrammatiko allows ICMP Echo requests, otherwise we have to cc him :))))

[dgrammatiko]

@Ruud68 looks fine.

FWIW HTML5 pattern validation was introduced in 2016 with #13094 and with the reasonable expectation that Joomla 4 will use it in every form. Obviously, this didn't happen and it's not down to the JS devs bus factor but rather to the fact that many devs introduce modern patterns (pun intended) but nobody is willing to follow them (in this case editing the XML files and adding the appropriate pattern="someRegEx" were the missing steps, and you can't blame the JS devs for not taking the huge load of work to make that happen).

[joomdonation]

I have tested this item ✅ successfully on 7c0fd21

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[Ruud68]

Thanks for testing @joomdonation

[Quy]

I have tested this item ✅ successfully on 7c0fd21

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_{This comment was created with the J!Tracker Application at issues.joomla.org/tracker/joomla-cms/34124.}

[Quy]

RTC

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[Ruud68]

Thanks for testing and RTC @Quy