fix(feedback): Remove sentry import from user feedback sdk snippets (#12946)

Removes the `@sentry/browser` imports making the snippets applicable to any
sdk package.

Closes: #9728

Author: andreiborza

platform-includes/user-feedback/sdk-api-example/javascript.mdx

@@ -1,6 +1,4 @@
 ```javascript {tabTitle: JavaScript}
-import * as Sentry from "@sentry/browser";
-
 // All feedback fields are optional, except `message`.
 const userFeedback = {
   name: "John Doe",
@@ -11,8 +9,6 @@ Sentry.captureFeedback(userFeedback);
 ```
 
 ```javascript {tabTitle: JavaScript with eventId}
-import * as Sentry from "@sentry/browser";
-
 const eventId = Sentry.captureException(new Error("Something went wrong!"));
 // OR: const eventId = Sentry.lastEventId();