Add test for monsoon

[ehogan]

Create a file for monsoon in https://github.com/MetOffice/CMEW/tree/main/CMEW/app/compare/opt to check that the following files exist:

• nac_plots/monsoon_east_indices.png
• nac_plots/monsoon_east.png
• nac_plots/monsoon_south_indices.png
• nac_plots/monsoon_south.png
• nac_plots/monsoon_east_other.png
• nac_plots/monsoon_overview.png
• nac_plots/monsoon_south_other.png
• u-bv526/metrics.csv
• u-cw673/metrics.csv

Acceptance criteria:

• Given the monsoon recipe works in CMEW
• When CMEW is run with the -o test option [should only test radiation_budget and monsoon]
• Then compare task runs to check if all the files as above are produced