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-front/src/modules/object-record/hooks/__mocks__/useFindManyRecords.ts

@@ -27,7 +27,6 @@ export const query = gql`
                 updatedAt
                 companyId
                 stage
-                probability
                 closeDate
                 amount {
                   amountMicros
@@ -53,7 +52,6 @@ export const query = gql`
                 updatedAt
                 companyId
                 stage
-                probability
                 closeDate
                 amount {
                   amountMicros