[JENKINS-73007] Create-item button no longer disabled when duplicate name present

[janfaracik]

See JENKINS-73007.

Missed this selector in #9111 - this PR fixes that so the submit button disables as expected. Tried to reproduce 73007 in an older version of Jenkins and couldn't sadly, the button was enabled despite the duplicate name. To fix this I've added enableSubmit(false); to set the button to be disabled when there's a duplicate item.

Testing done

• Button disables as expected, also when there's a duplicate project name
• Button enables as expected

Proposed changelog entries

• [JENKINS-73007] Create-item button no longer disabled when duplicate name present

Proposed upgrade guidelines

N/A

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[timja]

untested looks good though

[NotMyFault]

Thanks for the prompt fix!

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/label ready-for-merge

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This PR is now ready for merge. We will merge it after ~24 hours if there is no negative feedback.
Please see the merge process documentation for more information about the merge process.
Thanks!

[daniel-beck]

Create-item button no longer disabled when duplicate name present

I tried with 2.454 and this doesn't do what it claims it does:

It only disables the button if the name is edited after selecting a type, which should be exceedingly rare.

I filed JENKINS-73034.