refactor[cartesian]: descriptive loop names in dace backend

[romanc]

Description

The pipeline of representations (truncated) for the cartesian dace backend is as follows:

... > oir -> treeir (gt4py) -> schedule tree (dace) -> SDFG (dace)

In this PR, we change the names of map/loop in the schedule tree representation. The map/loop names in that representation are just names (that can more or less be anything). We had a rather general description and replace it with a more descriptive one, which includes the name of the stencil where the horizontal/vertical loop (sections) come from. This allows easier debugging and profiling. Nothing (except names) changes in the generated code. Thus no tests have been added.

This PR contains an unrelated commit removing unused imports from dace backend tests.

This PR is part of cleaning up our "working branch", i.e. #2595, which accumulated a couple of changes over the last month.

Requirements

• All fixes and/or new features come with corresponding tests.
  N/A
• Important design decisions have been documented in the appropriate ADR inside the docs/development/ADRs/ folder.
  N/A

[romanc]

cscs-ci run

[romanc]

cscs-ci run default

[twicki]

It makes sense to carry this information