Adjusted Per seat billing and added example to the sample schema

packages/billing/gateway/src/server/services/billing-gateway/billing-gateway.service.ts

@@ -127,16 +127,4 @@ export class BillingGatewayService {
 
     return strategy.updateSubscription(payload);
   }
-
-  /**
-   * Retrieves a plan by the specified plan ID.
-   * @param planId
-   */
-  async getPlanById(planId: string) {
-    const strategy = await BillingGatewayFactoryService.GetProviderStrategy(
-      this.provider,
-    );
-
-    return strategy.getPlanById(planId);
-  }
 }