Re-enabled Mac HTTPBIN tests

[LarryOsterman]

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[Copilot]

Pull Request Overview

Re-enables HTTPBIN tests on macOS by removing the platform‐specific disable directives.

• Removed the AZ_PLATFORM_MAC guard and _azure_DISABLE_HTTP_BIN_TESTS definition
• All HTTPBIN tests will now run on macOS

[antkmsft]

As of today, this is PR a test/experiment, correct? Because you've just merged a PR introducing it less than an hour ago, I believe, and now you're undoing the main thing from there. Should this PR be a Draft, or am I missing something?