In https://github.com/flutter/plugins/pull/3019 -Werror was incorrectly added directly to the plugin build itself, which impacts client builds. We've since updated our builds to set these flags on the project only when building our own example app, which gives us the CI benefits of this flag without burdening clients with restrictive build settings, so this is no longer needed.

Fixes https://github.com/flutter/flutter/issues/148478

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