dry_run: apply resolution changes to pixel_buffer

[jdries]

In this part of the dry run we extract the pixel buffer:

openeo-python-driver/openeo_driver/dry_run.py

Line 412 in 44dfa1e

constraints["pixel_buffer"] = {"buffer_size": buffer_size}

And then look up resampling parameters afterwards.

If a change of resolution occurs between pixel buffer and load_collection, the buffer needs to be adjusted accordingly.

A real world case is shown here:
Open-EO/openeo-geopyspark-driver#1452

[JeroenVerstraelen]

@soxofaan this is related to the load_stac refactor. Priority is not very high.