TST: Verify whether read-only datetime64 array can be factorized (35650) (#35775)
TST: Verify whether read-only datetime64 array can be factorized (35650) (#35775)

* TST: Verify whether read-only datetime64 array can be factorized (35650)

* CLN: Make test more inline with similar factorize tests
gfyoung/pandas,rs2/pandas,gfyoung/pandas,gfyoung/pandas,jreback/pandas,jreback/pandas,jorisvandenbossche/pandas,dsm054/pandas,pandas-dev/pandas,pandas-dev/pandas,rs2/pandas,pandas-dev/pandas,datapythonista/pandas,datapythonista/pandas,jorisvandenbossche/pandas,dsm054/pandas,rs2/pandas,jreback/pandas,jreback/pandas,dsm054/pandas,gfyoung/pandas,jorisvandenbossche/pandas,jreback/pandas,pandas-dev/pandas,gfyoung/pandas,jorisvandenbossche/pandas,rs2/pandas,dsm054/pandas,dsm054/pandas,datapythonista/pandas,datapythonista/pandas