Deprecate Probability field on Opportunity (#6207)

Closes #5735.
The field probability on opportunity will -
- stop being created for new workspaces (after this PR is merged)
- have "isCustom" value set to true and be displayed as such in the
settings (after this PR is merged + sync-metadata is run on workspace)
- still show in the views (all the time)

This field is deprecated as a standard field but not replaced by another
one, so we are not adding the `(deprecated)` suffix in the label.

packages/twenty-server/src/engine/workspace-manager/standard-objects-prefill-data/view-opportunity-fields.ts

@@ -47,16 +47,6 @@ export const viewOpportunityFields = (
       isVisible: true,
       size: 150,
     },
-    {
-      fieldMetadataId:
-        objectMetadataMap[STANDARD_OBJECT_IDS.opportunity].fields[
-          OPPORTUNITY_STANDARD_FIELD_IDS.probability
-        ],
-      viewId: viewId,
-      position: 4,
-      isVisible: true,
-      size: 150,
-    },
     {
       fieldMetadataId:
         objectMetadataMap[STANDARD_OBJECT_IDS.opportunity].fields[