fix(android): write lowercase booleans to the AndroidManifest

[bitsandfoxes]

Resolves #2843
Works around getsentry/sentry-android-gradle-plugin#1454

But is good cleanup, so, here we go.

[sentry]

Bug: The check in SetupSymbolsUpload is outdated and doesn't validate the DSN, causing symbol uploads to be configured even when the native SDK is not included.
_{Severity: MEDIUM}

Suggested Fix

Update the conditional check in the SetupSymbolsUpload method to use AndroidSdkEnabled. This property correctly validates that a DSN is present by calling _options.IsValid(), aligning its behavior with other methods like AddAndroidSdkDependencies and ensuring symbol uploads are only configured when the native SDK is properly enabled.

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: src/Sentry.Unity.Editor/Android/AndroidManifestConfiguration.cs#L573-L576

Potential issue: The `SetupSymbolsUpload` method contains an outdated conditional check,
`_options is not { Enabled: true, AndroidNativeSupportEnabled: true }`. Unlike other
related methods that were updated to use `AndroidSdkEnabled` (which validates the DSN
via `_options.IsValid()`), this check does not validate the DSN. As a result, if
`Enabled` and `AndroidNativeSupportEnabled` are true but the DSN is empty, the symbol
upload task will be configured even though the native SDK dependencies are not included
in the build. This creates an inconsistency introduced by the new changes.