TST: Update IntervalArray min/max test to fail on changed default skipna

[jsngn]

• [x] Part of #58517
• [x] Tests added and passed if fixing a bug or adding a new feature
• [x] All code checks passed.
• [x] ~Added type annotations to new arguments/methods/functions.~ Not applicable
• [x] ~Added an entry in the latest doc/source/whatsnew/vX.X.X.rst file if fixing a bug or adding a new feature.~ Not applicable

Before, if the line core/arrays/interval.py:866 is changed from def min(self, *, axis: AxisInt | None = None, skipna: bool = True) -> IntervalOrNA: to def min(self, *, axis: AxisInt | None = None, skipna: bool = False) -> IntervalOrNA:, all tests still passed. Now they will fail if the default skipna param is updated, perhaps mistakenly.

Applies to max() method too since they are tested in the same test function.

[jsngn]

@mroeschke Could you take a look? Thank you!

[mroeschke]

Thanks @jsngn