Fix canary Lambda invoke success check

[jdisanti]

Motivation and Context

It seems Lambda's Invoke returns a status 200 even when the function fails with exit status 1, but at the same time, it responds with function_error set. I tested this by uploading a trivial Rust binary that just exits with status 1 to Lambda and invoking it, which resulted in:

[src/main.rs:18] result = Ok(
    InvokeOutput {
        status_code: 200,
        function_error: Some(
            "Unhandled",
        ),
        // -- snip --
    },
)

This PR fixes the check in canary-runner.

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• AWS SDK (ignoring whitespace)
• No codegen difference in the Server Test
• No codegen difference in the Server Test Python

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[github-actions]

A new generated diff is ready to view.

• AWS SDK (ignoring whitespace)
• No codegen difference in the Server Test
• No codegen difference in the Server Test Python

A new doc preview is ready to view.