Hide "Using a framework?" message box on Spring and Spring Boot onboarding guides" (#12645)

* ref(java): separate Spring and Spring Boot pages to their own `index.mdx`

* Revert "ref(java): separate Spring and Spring Boot pages to their own `index.mdx`"

This reverts commit 165b239.

* Hide "Using a framework?" message box on Spring and Spring Boot onboarding guides

Author: lcian

docs/platforms/java/common/index.mdx

@@ -2,7 +2,9 @@
 
 On this page, we get you up and running with Sentry's SDK.
 
+<PlatformSection notSupported={["java.spring", "java.spring-boot"]}>
 <PlatformContent includePath="alert-using-a-framework" noGuides />
+</PlatformSection>
 
 Don't already have an account and Sentry project established? Head over to [sentry.io](https://sentry.io/signup/), then return to this page.