chore: update ecommerce updateProductStock scopes + quantity

[2ynn]

the updateProductStock endpoint in ecommerce.yaml is not yet used for testing oauth2-password authentication:

• typescriptV2
• javaV2

The motivation behind this change is to allow testing with oauth2:password as a security option alongside other schemes, e.g.:

  - target: $.paths.*.*[?(@.operationId == 'updateProductStock')]
    update:
      security:
        - oauth2Password1: [admin]
        - oauth2Password2: [products:udpate]