fix: getPayload generate import map only when used in Payload Admin Panel (#9371)

After the change with removing `getPayloadHMR`, we do generate import
map even outside of Next.js, which leads to errors when using in a
project without it:

![image](https://github.com/user-attachments/assets/e8dc2af6-566b-443c-a6d8-8b02e719bd30)

packages/payload/src/index.ts

@@ -807,7 +807,7 @@ export const getPayload = async (
       // will reach `if (cached.reload instanceof Promise) {` which then waits for the first reload to finish.
       cached.reload = new Promise((res) => (resolve = res))
       const config = await options.config
-      await reload(config, cached.payload)
+      await reload(config, cached.payload, !options.importMap)
 
       resolve()
     }
@@ -815,7 +815,6 @@ export const getPayload = async (
     if (cached.reload instanceof Promise) {
       await cached.reload
     }
-
     if (options?.importMap) {
       cached.payload.importMap = options.importMap
     }
@@ -839,6 +838,7 @@ export const getPayload = async (
     ) {
       try {
         const port = process.env.PORT || '3000'
+
         cached.ws = new WebSocket(
           `ws://localhost:${port}${process.env.NEXT_BASE_PATH ?? ''}/_next/webpack-hmr`,
         )