lfric2um does not need stencil depth of 2

### Are there any linked Issues or Pull Requests?

_No response_

### Brief description

lfricinputs sets stencil_depth=2 for all three apps.

lfric2um does not use stencils, so stencil_depth=1 is adequate. It seems to save about 10 seconds in setup time when running C896 on 108 Genoa nodes, so worthwhile. Impact on memory is minimal (the extra halo increases the local volume by about 1 per cent).

May need to see impact on other apps, and require each app to have its own setting if necessary.

### Further details of the issue.

Blocked by Issue #694 - work on this ticket exposed an error in the regridding of STASH code 265 in lfric2um
Also, the change makes minor changes to edge ordering of output from `um2lfric` that should have no impact on cell centre fields but breaks nccmp KGO checking. Can be fixed by adding an extra ignore to the `nccmp` invocation to ignore differences in `Mesh2d_edge_nodes`.

_No response_