DD-1783: blocked page because of not found host dataverse

[jo-pol]

What this PR does / why we need it:

A dataset is not saved and there is no option to correct the mistake if you edit the “Host Dataverse” field and immediately correct and leave it. When clicking Save the page freezes and after a hard refresh all your metadata is gone and you have to start over. Reproduced in 6.3 and 6.5 (DANS branches).

Which issue(s) this PR closes:

• Closes #

Special notes for your reviewer:

Not sure about the impact when templates are used. See IQSS#11301 (comment)

Suggestions on how to test this:

1. In the user interface click Add Data → New Dataset
2. The cursor is placed in the “Host Dataverse” field.
3. Type a space, remove it and quickly put the cursor in the title field.
4. Fill in the required fields and click Save.

Not tested with templates.

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

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

Additional documentation:

@DANS-KNAW/core-systems

[coveralls]

Pull Request Test Coverage Report for Build #151

Details

• 0 of 5 (0.0%) changed or added relevant lines in 2 files are covered.
• 2 unchanged lines in 1 file lost coverage.
• Overall coverage decreased (-0.001%) to 22.536%

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Changes Missing Coverage	Covered Lines	Changed/Added Lines	%
src/main/java/edu/harvard/iq/dataverse/DatasetPage.java	0	2	0.0%
src/main/java/edu/harvard/iq/dataverse/DataverseConverter.java	0	3	0.0%

Files with Coverage Reduction	New Missed Lines	%
src/main/java/edu/harvard/iq/dataverse/pidproviders/doi/ezid/EZIdDOIProvider.java	2	6.12%

Totals
Change from base Build #141:	-0.001%
Covered Lines:	19542
Relevant Lines:	86714

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💛 - Coveralls