Revise test markers

[ansjsia]

Implement the following changes in test markers to remove markers with little utility and to improve clarity for intended use:

1. Change the name of the setup marker to settings_only.
2. If the test initializes or solves the case, remove the settings_only marker.
3. Update the description of the settings_only marker to “Read and modify the case settings only without loading the mesh, initializing, or solving the case.”
4. Remove the following markers from all tests that use them and from pyproject.toml:
   1. integration (6 tests)
   2. quick (11 tests)
   3. solve (no tests)
   4. mesh (1 test)
   5. optislang (2 tests)

This should not be merged until after PR #2296 is merged because it makes changes to whether some tests initialize or solve.
EDIT: #2296 has been merged.