Fix schema.

Signed-off-by: Aramis Sennyey <sennyeya@amazon.com>

plugins/catalog-backend/openapi.yaml

@@ -255,7 +255,7 @@ components:
         items:
           type: array
           items:
-            allOf:
+            anyOf:
               - $ref: '#/components/schemas/Entity'
               - type: 'null'
           description: |-

plugins/catalog-backend/schema/openapi.ts

@@ -524,8 +524,7 @@ export default {
               'A text to show to the user to inform about the choices made. Like, it could say\n"Found a CODEOWNERS file that covers this target, so we suggest leaving this\nfield empty; which would currently make it owned by X" where X is taken from the\ncodeowners file.',
           },
           value: {
-            type: 'string',
-            nullable: true,
+            type: ['string', 'null'],
           },
           state: {
             type: 'string',