[release/9.0] Remove invalid assert in RSAOpenSsl

[github-actions]

Backport of #107932 to release/9.0

/cc @vcsjones

Customer Impact

• Customer reported
• Found internally

Regression

• Yes
• No

Failing test reported in #107929 and #105715. An assert existed that a particular SafeHandle is valid, however this is not true in a multi-threaded case where the handle is disposed and used concurrently. This assert would occasionally be hit in unit tests.

SafeHandles handle thread safety, correctly, on their own. We should remove the assert and let the ObjectDisposedException from the SafeHandle happen.

Testing

Existing tests continue to pass.

Risk

None / Low. The change removes a Debug.Assert which is only present in Debug builds of Libraries.

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[carlossanlop]

That was a fast fix!