Allow save of empty translations for dictionary items (#18980)

* Allow save of empty translations for dictionary items.

* Updated Open API schema to match request model update

---------

Co-authored-by: kjac <[email protected]>

Author: AndyButland

src/Umbraco.Cms.Api.Management/OpenApi.json

@@ -37181,7 +37181,6 @@
             "type": "string"
           },
           "translation": {
-            "minLength": 1,
             "type": "string"
           }
         },

src/Umbraco.Cms.Api.Management/ViewModels/Dictionary/DictionaryItemTranslationModel.cs

@@ -1,4 +1,4 @@
-using System.ComponentModel.DataAnnotations;
+using System.ComponentModel.DataAnnotations;
 
 namespace Umbraco.Cms.Api.Management.ViewModels.Dictionary;
 
@@ -7,6 +7,5 @@ public class DictionaryItemTranslationModel
     [Required]
     public string IsoCode { get; set; } = string.Empty;
 
-    [Required]
     public string Translation { get; set; } = string.Empty;
 }