skip premature validation of required drop downs in metadata blocks

[jo-pol]

…mandatory

What this PR does / why we need it:

It skips a premature validation phase for a metadata block field with a mandatory drop down. This allows proper template change for a blank dataset and gives clearer error messages when saving.

Which issue(s) this PR closes:

Closes #10119

Special notes for your reviewer:

The HTML attribute required triggers a premature validation in metadata blocks. The db-table datasetfieldtype controls the desired validation phase.

Suggestions on how to test this:

Have a required field in a metadatablock (e.g. type of article in the journal block) and a custom template that should set a field(s) in the citation block (e.g. title). Create a new dataset, set none of the fields and change to the custom template, the title should be applied. Save the blank dataset and a clear error message appears for the type of article.

Does this PR introduce a user interface change? If mockups are available, please link/include them here:

no

Is there a release notes update needed for this change?:

no

Additional documentation:

[qqmyers]

Nice find! As discussed, this change fixes a clear bug. I'll note it also aligns the single value case with the multi-value one (which already has no required attribute). I've also tested this at QDR and seen that it resolves the issue.

[qqmyers]

@jo-pol - why did you close this?

[jo-pol]

I cleaned up in Intellij and wasn't aware this wasn't a stale branch. Thanks for the heads up.

[jo-pol]

Reopened with #10210 Sorry for the inconvenience of going through the review process again. I marked the branch name to reduce the chance it happens again.