Exclude FGOALS-g2 due to ESMValCore issue #728

[mattiarighi]

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Please discuss your idea with the development team before getting started, to avoid disappointment later. The way to do this is to open a new issue on GitHub. If you are planning to modify an existing functionality, please discuss it with the original author(s) by tagging them in the issue.

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Tasks

• Create an issue to discuss what you are going to do, if you haven't done so already (and add the link at the bottom)
• Give this pull request a descriptive title that can be used as a one line summary in a changelog
• Make sure your code is composed of functions of no more than 50 lines and uses meaningful names for variables
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• Please use yamllint to check that your YAML files do not contain mistakes
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• If new dependencies are introduced, check that the license is compatible with Apache2.0

Workaround for #1743.