Deal more gracefully when index.mapping.field_name_length.limit is exceeded. #135700
Description
Today when the index.mapping.field_name_length.limit index setting is specified and it gets exceeded, then indexing fails with a client error. This behavior should be changed, so that instead of failing, the field that exceeded the max length should be ignored. There is already infrastructure for ignoring documents in case of validation fails and we should picky bag that. The result would be that the field will not be mapped and only be accessible in the _source.