REGR: fix period dtype <-> arrow roundtrip for pyarrow < 4
Closes #45470
Is this ready? can we merge and get this backported or move to 1.4.1 before tomorrow morning since if still open and on the 1.4 milestone tomorrow I will not start the release. @meeseeksdev backport 1.4.x Something went wrong ... Please have a look at my logs.