Fixing session replay responsiveness in code blocks (#14406)

## DESCRIBE YOUR PR
Session replay code was showing up in the code blocks whether or not
`session replay` was selected as a feature to install.

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- [ ] Other deadline: <!-- ENTER DATE HERE -->
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## PRE-MERGE CHECKLIST

*Make sure you've checked the following before merging your changes:*

- [ ] Checked Vercel preview for correctness, including links
- [ ] PR was reviewed and approved by any necessary SMEs (subject matter
experts)
- [ ] PR was reviewed and approved by a member of the [Sentry docs
team](https://github.com/orgs/getsentry/teams/docs)

---------

Co-authored-by: Shannon Anahata <[email protected]>

Author: sfanahata

docs/platforms/javascript/guides/nextjs/index.mdx

@@ -69,6 +69,7 @@ Sentry.init({
     Sentry.browserTracingIntegration(),
     // ___PRODUCT_OPTION_END___ performance
     // ___PRODUCT_OPTION_START___ session-replay
+    // Replay may only be enabled for the client-side
     Sentry.replayIntegration(),
     // ___PRODUCT_OPTION_END___ session-replay
     // ___PRODUCT_OPTION_START___ user-feedback
@@ -93,8 +94,7 @@ Sentry.init({
   tracesSampleRate: 1.0,
   // ___PRODUCT_OPTION_END___ performance
   // ___PRODUCT_OPTION_START___ session-replay
-
-  // Capture Replay for 10% of all sessions,
+  // Capture Replay for 10% of all 
   // plus for 100% of sessions with an error
   // Learn more at
   // https://docs.sentry.io/platforms/javascript/session-replay/configuration/#general-integration-configuration

docs/platforms/javascript/guides/nextjs/manual-setup.mdx

@@ -127,25 +127,26 @@ Sentry.init({
   // https://docs.sentry.io/platforms/javascript/configuration/options/#traces-sample-rate
   tracesSampleRate: 1.0,
   // ___PRODUCT_OPTION_END___ performance
-  // ___PRODUCT_OPTION_START___ session-replay
-  // Replay may only be enabled for the client-side
   integrations: [
+    // ___PRODUCT_OPTION_START___ session-replay
+    // Replay may only be enabled for the client-side
     Sentry.replayIntegration(),
+    // ___PRODUCT_OPTION_END___ session-replay
     // ___PRODUCT_OPTION_START___ user-feedback
     Sentry.feedbackIntegration({
       // Additional SDK configuration goes in here, for example:
       colorScheme: "system",
     }),
     // ___PRODUCT_OPTION_END___ user-feedback
   ],
+  // ___PRODUCT_OPTION_START___ session-replay
 
   // Capture Replay for 10% of all sessions,
   // plus for 100% of sessions with an error
   // Learn more at
   // https://docs.sentry.io/platforms/javascript/session-replay/configuration/#general-integration-configuration
   replaysSessionSampleRate: 0.1,
   replaysOnErrorSampleRate: 1.0,
-
   // ___PRODUCT_OPTION_END___ session-replay
   // ___PRODUCT_OPTION_START___ logs