fix: allow more data types in the variable default field (#1644)

Because

- the default value in the variable section can represent various data
types.

This commit

- expands support for additional data types in the variable default
field. Since the default value can be of any data type, we remove the
`type` limitation.

packages/toolkit/src/view/recipe-editor/lib/schema.ts

@@ -90,9 +90,7 @@ export const InstillYamlSchema = {
             description: {
               type: "string",
             },
-            default: {
-              type: "string",
-            },
+            default: {},
             "instill-ui-multiline": {
               type: "boolean",
             },