root user 100 project limit is too small for development

The root user project limit is seeded to 100 which is too easy to run into with a long-running GDK.

This message will appear as an orange banner when you run into the limit,

You won't be able to create new projects because you have reached your project limit.

We should update it to 100000 to match the Gitlab::CurrentSettings.default_projects_limit.

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https://gitlab.slack.com/archives/C02PF508L/p1518639258000163