Retention period default date issues

What steps does it take to reproduce the issue? Wile testing #12421, two related issues were discovered w.r.t. the default/suggested date when setting a retention period. First, when intially launched the retention dialog shows a date one day after the minimum allowed date, e.g. Nov 19 instead of 18 (which is allowed) in:

Second, if the dialog is closed and reopened, the default changes to 1000 years in the future:

• When does this issue occur?
  Editing the retention period.

• Which page(s) does it occurs on?
  Dataset and file pages.

• Why does it happen?

Due to

dataverse/src/main/java/edu/harvard/iq/dataverse/DatasetPage.java

Line 2307 in 0b87f4b

selectionRetention.setDateUnavailable(minRetentiondate.plusDays(1L));
and
dataverse/src/main/java/edu/harvard/iq/dataverse/FilePage.java

Line 296 in 0b87f4b

selectionRetention.setDateUnavailable(minRetentiondate.plusDays(1L));
, the initial choice for retention period is the day after the minimum - seems like plusDays(1) isn't needed if the minimum now has a minusDays(1).
If I cancel the retention dialog and reopen it, the default date shown is 1000 years in the future. I think that's due to creation of a new Retention at

dataverse/src/main/java/edu/harvard/iq/dataverse/DatasetPage.java

Line 6849 in 0b87f4b

selectionRetention= new Retention();
(which defaults to 1000 years in the constructor), without code like this
dataverse/src/main/java/edu/harvard/iq/dataverse/DatasetPage.java

Lines 2305 to 2308 in 0b87f4b

LocalDate minRetentiondate = settingsWrapper.getMinRetentionDate();
if (minRetentiondate != null){
selectionRetention.setDateUnavailable(minRetentiondate.plusDays(1L));
}
which is done at page init but not in the clearRetentionPopup method. (Similar issue with the FilePage.)
As these are all retention date related and relatively simple, would you like to fix them in this PR, or do you want to treat them as a separate issue/possible PR for the future?

Which version of Dataverse are you using?
6.11+ / develop

Any related open or closed issues to this bug report?

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Are you thinking about creating a pull request for this issue?
Help is always welcome, is this bug something you or your organization plan to fix?
Just capturing the issue at present.

Start in DatasetPage.java and FilePage.java, reading the retention dialog initialization and clearRetentionPopup methods, especially setDateUnavailable and new Retention. Verify the minimum allowed date is shown on first open and that reopening the dialog does not reset the date to 1000 years ahead on dataset and file pages.