Update Sentry SDK integration instructions for frontend: generalize p… (#15614)

This pull request updates the Sentry integration documentation for
frontend applications to improve clarity and remove unnecessary code
comments. The most important changes are:

**Documentation clarity improvements:**

* Updated the instructions to install the Sentry React SDK to use the
more general term "package manager" instead of specifically "NPM" in
`docs/product/sentry-basics/integrate-frontend/initialize-sentry-sdk.mdx`.

**Code cleanup:**

* Removed an unused code comment include for trace sample rate
configuration from the Sentry initialization code example in
`docs/product/sentry-basics/integrate-frontend/initialize-sentry-sdk.mdx`.

Author: KyleTryon

docs/product/sentry-basics/integrate-frontend/initialize-sentry-sdk.mdx

@@ -30,7 +30,7 @@ The sample application is a basic frontend-only application using React and webp
 
 Sentry captures data by using a platform-specific SDK that you add to your application's runtime. To use the SDK, import and configure it in your source code. This demo project uses [Sentry's React SDK](https://github.com/getsentry/sentry-javascript/tree/develop/packages/react).
 
-1. Install the Sentry React SDK using NPM.
+1. Install the Sentry React SDK using a package manager.
 
    Make sure you're in the `frontend-tutorial` project folder.
 
@@ -69,15 +69,11 @@ Sentry captures data by using a platform-specific SDK that you add to your appli
      // https://docs.sentry.io/platforms/javascript/session-replay/configuration/#general-integration-configuration
      replaysSessionSampleRate: 0.1,
      replaysOnErrorSampleRate: 1.0,
-     ${<Include name="code-comments/javascript/trace-sample-rate" />}
    });
    ```
 
    It's important to import and initialize the SDK as early as possible in your application's lifecycle so Sentry can capture errors throughout the lifecycle. <Include name="platforms/configuration/options/js-config-options" />
 
-
-
-
 1. Add your DSN key to the Sentry SDK configuration.
 
    Paste in the DSN key value you copied from the project created in the [previous section](/product/sentry-basics/integrate-frontend/create-new-project/).