Fix IsSupported unit test for Android's X25519 implementation

[vcsjones]

Fixes #131633

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[Copilot]

Pull request overview

Updates the X25519 IsSupported_AgreesWithPlatform unit test to avoid asserting a fixed support expectation on Android API levels < 33, where Conscrypt may provide XDH support via out-of-band updates even when the documented platform floor says otherwise.

Changes:

• Adds an early-return guard for Android < API 33 so either true or false is treated as acceptable on those OS versions.
• Keeps the existing expectation that Android API 33+ should report support.

Show a summary per file

File	Description
src/libraries/Common/tests/System/Security/Cryptography/X25519DiffieHellmanImplementationTests.cs	Skips the strict platform agreement assertion on Android versions earlier than API 33 to prevent false failures.

Copilot's findings

• Files reviewed: 1/1 changed files
• Comments generated: 0