• Closes PerformanceWarning in da.to_zarr is misleading and stops (correct?) execution #12160
• Tests passed (main fails them as well)
• Passes pre-commit run --all-files

On main, the following code leads to an exception:

import dask.array as da
import zarr

output_zarr_array = zarr.create(
    shape=(8,),
    chunks=(5,),
    overwrite=True,
)

x = da.ones((5,), chunks=(5,))

da.to_zarr(
    x,
    output_zarr_array,
    region=tuple([slice(0, 5)]),
    )

PerformanceWarning: The input Dask array will be rechunked along axis 0 with chunk size 8, but a chunk size divisible by 5 is required for Dask to write safely to the Zarr array <Array memory://4933780544 shape=(8,) dtype=float64>. To avoid risk of data loss when writing to this Zarr array, set the "array.chunk-size" configuration parameter to at least the size in bytes of a single on-disk chunk (or shard) of the Zarr array, which in this case is 40 bytes. E.g., dask.config.set({"array.chunk-size": 40})

This PR

1. Prevents execution stop by replacing raise by warnings.warn
2. Takes region= into account for the performance warning.