Fix 400 error when editing Leadership page

This changset increases the number of form fields allowed to be submitted
in one GET/POST, but only for deployments where the CMS is enabled.

This is needed to support complex pages with lots of (small, but) nested
fields.

Ref: https://mozilla.sentry.io/issues/5800147294

bedrock/settings/base.py

@@ -2098,6 +2098,12 @@ def before_send(event, hint):
         ]
     )
 
+    # Increase the number of form fields allowed to be submitted in one GET/POST,
+    # but only for deployments where the CMS is enabled. This is needed to support
+    # complex pages with lots of (small, but) nested fields.
+    # Resolves https://mozilla.sentry.io/issues/5800147294
+    DATA_UPLOAD_MAX_NUMBER_FIELDS = 2000
+
 
 def lazy_wagtail_langs():
     enabled_wagtail_langs = [