Swap 'merged dtype same as NumPy' test of v1 for test of v2.

[jpivarski]

Inspired by #1514 (comment).

[codecov]

Codecov Report

Merging #1515 (848a6c4) into main (0c6ae03) will decrease coverage by 0.03%.
The diff coverage is 21.42%.

Impacted Files	Coverage Δ
...awkward/_v2/_connect/rdataframe/from_rdataframe.py	0.00% <0.00%> (ø)
...c/awkward/_v2/_connect/rdataframe/to_rdataframe.py	0.00% <0.00%> (ø)
src/awkward/_v2/_connect/cling.py	25.99% <9.09%> (-0.35%)	⬇️
src/awkward/_v2/_lookup.py	97.51% <100.00%> (+0.01%)	⬆️
src/awkward/_v2/types/__init__.py	100.00% <100.00%> (ø)
src/awkward/_v2/types/recordtype.py	87.03% <100.00%> (+0.79%)	⬆️
src/awkward/_v2/highlevel.py	73.70% <0.00%> (+0.16%)	⬆️