Remove modular building option

[kounelisagis]

Removes the --modular option when building TileDB-Py.

[shortcut-integration]

This pull request has been linked to Shortcut Story #43445: Remove deprecated cython IF usage.

[nguyenv]

I understand the IF keyword is deprecated in Cython now, but does that mean we need to get rid of the TILEDBPY_MODULAR option? I also have never toggled TILEDBPY_MODULAR so don't have any context for how that macro is used.

[kounelisagis]

I understand the IF keyword is deprecated in Cython now, but does that mean we need to get rid of the TILEDBPY_MODULAR option? I also have never toggled TILEDBPY_MODULAR so don't have any context for how that macro is used.

After discussed with @ihnorton, we will remove the whole TILEDBPY_MODULAR option.

[ihnorton]

@nguyenv this is untested/unmaintained, and was always kind of brittle; not necessary now with pybind work.

[ihnorton]

Thanks