Reapply !53803 Allow saving repository weights after a storage has been removed - [RUN ALL RSPEC] [RUN AS-IF-FOSS]

What does this MR do?

Reapplies !53803 (merged) that was previously reverted in !55662 (merged) as it broke various background migration specs in master.

This MR has an additional fix in a separate commit to change the default for the hstore field. hstore can only have string keys, but rails will allow symbol keys in memory. This was causing the filtering to fail as the default had symbol keys and the filter expects strings.

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Does this MR meet the acceptance criteria?

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