Handle recarrays for automatically generated tests in a single place

[eerovaher]

In some of the tests created by erfa_generator arrays should be viewed as recarrays so that data in them could be accessed by named attributes. On current main creating the recarrays is handled in two different TestFunction methods, but in this PR it is done in just one. There are two small changes to the generated test_ufunc.py file:

421c421
<     astrom = np.zeros((), erfa_ufunc.dt_eraASTROM).view(np.recarray)
---
>     astrom = np.empty((), erfa_ufunc.dt_eraASTROM).view(np.recarray)
430c430
<     astrom = np.zeros((), erfa_ufunc.dt_eraASTROM).view(np.recarray)
---
>     astrom = np.empty((), erfa_ufunc.dt_eraASTROM).view(np.recarray)

The changes are in the test_aper() and test_aper13() functions. From what I can tell in both cases the new versions of the generated tests are more similar to the ERFA C tests than the old versions.