Style: fix flake8 E128 and isort drift in interpolate/_kriging.py

[brendancol]

_kriging.py has two style issues that the project's configured tooling reports but CI does not gate:

• flake8 E128 (continuation line under-indented for visual indent) at two call sites in the dask backend wrappers: the _chunk_var helpers in _kriging_dask_numpy and _kriging_dask_cupy.
• isort import drift: the from xrspatial.utils import (...) block is wrapped across several lines but fits on one line under the configured line_length=100.

Both fixes are behaviour-neutral. Re-indent the two continuation lines and collapse the import to a single line.

setup.cfg sets max-line-length=100 and isort line_length=100, but neither runs in CI, so the drift stayed invisible.