[ArrowStringArray] fix test_astype_int, test_astype_float
the changes to to_numpy are implicitly tested (and different behavior to StringArray). will need to add tests to explicitly tests this with the changes requested here. will open separate PRs for to_numpy/astype and close this to clear the queue. merging, @simonjayhawkins if you can note the followups > merging, @simonjayhawkins if you can note the followups

sure. The typing is included in https://github.com/pandas-dev/pandas/issues/35169#issuecomment-727217462 and will be done after the work by @Dr-Irv sorting out the base EA types.
