Add `recipe_ocean_multimap` to RTW

[chrisbillowsMO]

Add the recipe_ocean_multimap recipe to the Recipe Test Workflow.

This was done while testing the documentation for #3074 and it works (hooary) so now adding for real.

These are the changed required.

@@ -12,7 +12,8 @@
         recipe_heatwaves_coldwaves, \
         recipe_autoassess_landsurface_soilmoisture, \
         recipe_consecdrydays, \
-        examples--recipe_python
+        examples--recipe_python, \
+        recipe_ocean_multimap
     medium = recipe_ensclus  # Should be in fast: is in medium temporarily to
                              # avoid empty variable.

diff --git a/esmvaltool/utils/recipe_test_workflow/recipe_test_workflow/site/metoffice.cylc b/esmvaltool/utils/recipe_test_workflow/recipe_test_workflow/site/metoffice.cylc
index c967a0b3b..df981c964 100644
--- a/esmvaltool/utils/recipe_test_workflow/recipe_test_workflow/site/metoffice.cylc
+++ b/esmvaltool/utils/recipe_test_workflow/recipe_test_workflow/site/metoffice.cylc
@@ -40,6 +40,12 @@
         execution time limit = PT2M
         [[[directives]]]
             --mem = 3G
+    
+    [[process<fast=recipe_ocean_multimap>]]
+        # Actual: 6m52.260589s, 2.5 GB on 2024-05-28.  
+        execution time limit = PT8M
+        [[[directives]]]
+            --mem = 3G

     [[process<medium=recipe_ensclus>]]