tests on GPU - remove Fields.bycolumn

[LenkaNovak]

This is supposed to improve CPU performance when using threading. However, the gains are most likely marginal and this is not GPU compatible when other operators are being performed on the column (i.e. colidx is ignored on GPU). See #735 for an example of this problem and suggested solutions

Tests on GPU

bycolumn is also preventing GPU compatibility in flux_calculator_tests.jl and eisenman_seaice_tests.jl. Removing it should make those GPU compatible.

Solution

We can either remove the bycolumn loop completely, or replace this with Operators.column_mapreduce!. If it's not performant critical code, we could use Spaces.column

QA

• make note of performance changes, both for CPU and GPU. Buildkite total job time suffices

[LenkaNovak]

also see CliMA/ClimaCore.jl#1609