feat(tracemetrics): Add Java and Android to supported platforms

[adinauer]

Legal Boilerplate

Look, I get it. The entity doing business as "Sentry" was incorporated in the State of Delaware in 2015 as Functional Software, Inc. and is gonna need some rights from me in order to utilize my contributions in this here PR. So here's the deal: I retain all rights, title and interest in and to my contributions, and by keeping this boilerplate intact I confirm that Sentry can use, modify, copy, and redistribute my contributions, under Sentry's choice of terms.

[sentry]

Bug: Adding 'android' to withMetricsOnboarding is incorrect as the Android docs module lacks a metricsOnboarding export, leading to a blank page for users.
_{Severity: MEDIUM}

Suggested Fix

Remove 'android' from the withMetricsOnboarding set. This change should be reverted until the Android documentation module is updated to include and export the metricsOnboarding content.

Prompt for AI Agent

Review the code at the location below. A potential bug has been identified by an AI
agent.
Verify if this is a real issue. If it is, propose a fix; if not, explain why it's not
valid.

Location: static/app/data/platformCategories.tsx#L386

Potential issue: The code change adds 'android' to the `withMetricsOnboarding` set,
which signals that metrics onboarding documentation is available for the Android
platform. However, the corresponding documentation module for Android, located at
`static/app/gettingStartedDocs/android/index.tsx`, does not export a `metricsOnboarding`
property. When a user with an Android project attempts to view this documentation, the
`useLoadGettingStarted.ts` hook will successfully load the module but will find that
`module.default.metricsOnboarding` is `undefined`. This results in the user being shown
no content, creating a broken user experience.

_{Did we get this right? 👍 / 👎 to inform future reviews.}