Fix default for repetition_start_date

[eileenmcnaughton]

Overview

Fix default not loading for start date on event repeat pane. It should default to the current event start date but due to date mishandling this is not happening

Before

After

Technical Details

I think this is a regression from #12746 hence I put it against the rc which contains that fix. It's pretty trivial so should be rc-safe

Comments

@colemanw @mattwire you were both involved in the earlier one. Note there might be other affected places because the original PR focussed on recurring entities from the activity screen but I'm not sure what other screens support it. Also, possibly CiviVolunteer?

[civibot]

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[colemanw]

This fix is consistent with all the other work that's been done in this area, makes sense and tests pass.