fix multi-level redirect in server actions (#72770)
`redirect` in server actions has handling to support relative redirects
(eg `redirect('./foo')`) but it doesn't handle a multi-level relative
path, eg `redirect('../foo')`.
This used to work by accident because the invalid URL would be handled
as an error and then would trigger an MPA navigation. In Next 15, it
surfaces an actual error because we are less tolerant to them.
Fixes #72765
Closes NDX-479
