DEPR: remove Int/Uint/Float64Index from pandas/tests/indexing & pandas/tests/series
Extraction of part of #50479. Progress towards #42717.
Thanks @topper-123  Great, It's getting close now to removing Int64Index & friends. Only outstanding big issue is arithemetic with indexes with bit-size lower than 64-bit. I hope I can get that done tomorrow or saturday. 