Allow postgresraster layers as grass processing tools input

[JanCaha]

Description

This is same fix as in #57958 just for Grass Processing tools.

This makes sure that that the input parameter for r.in.gdal step is properly formatted GDAL connection string even for postgresraster provider.

Funded by Ocean Winds

[github-actions]

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(Built from commit 374f2a0)

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[elpaso]

Looks good to me, Is there any chance you could write a test for this?

[JanCaha]

@elpaso That should not be a problem. I am just a bit unsure about the type of the test.

Would it be ok to write test file like this one: https://github.com/uclaros/QGIS/blob/e81c8a1b659cb278e852451392cb8b37134d5b84/tests/src/python/test_processing_algs_gdal_gdalutils.py
and within that file run one of the grass algorithms using:

from qgis import processing
processing.run( )

Or is something more elaborate necessary? In that case I could really use pointer to some example.

Thanks.

[elpaso]

It's up to you, you may also have a look to the processing tests like: python/plugins/processing/tests/GdalAlgorithmsRasterTest.py and python/plugins/processing/tests/testdata/gdal_algorithm_raster_tests.yaml

[JanCaha]

Ok, tests are added .