Explore transmute further with aerosol_ukca_kernel_mod conv_comorph_kernel_mod

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

Umbrella: #424
PR: #691

### Brief description

https://github.com/MetOffice/lfric_apps/pull/607 has run into issues compiling `aerosol_ukca_kernel_mod` and `conv_comorph_kernel_mod` after they have been Transmuted with CCE.

After discussing possible causes with STFC, we think the best course is to:
- Explore `MaximalOMPParallelRegionTrans` to reduce parallel sections - https://github.com/MetOffice/lfric_apps/compare/main...MetBenjaminWent:lfric_apps:aero_ukca_conv_como_explore
- _See if GCC is affected - Not thought so currently!_
- Reduce optimisation with CCE: Lower `-h ipalevel` to 0 or increase `-m msg_level` to 4
- See if Transmuted, but no optmisation, fails

### Further details of the issue.

_No response_