fix(import): clarify global field reference-field warning message

Reword the warning logged when a referenced content type is not yet
imported so it no longer implies permanent data loss. The reference is
deferred and restored later in the same run, so the previous
"Removing the field from schema..." wording was misleading.

DX-10153

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

Author: harshithad0703

packages/contentstack-import/src/utils/content-type-helper.ts

@@ -132,7 +132,7 @@ export const removeReferenceFields = async function (
           } catch (error) {
             // Else warn and modify the schema object.
             isContentTypeError = true;
-            log.warn(`Content type ${schema[i].reference_to[j]} does not exist. Removing the field from schema...`);
+            log.warn(`Content type ${schema[i].reference_to[j]} is not imported yet; its reference will be restored once it is imported.`);
           }
         }