Correct field type, add some missing fields to settings

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According to the docs (https://docs.gitlab.com/api/settings/#available-settings) the type of git_rate_limit_users_alertlist is an array of integers. However, in the code it's mapped to an array of strings. This is causing it to fail to json unmarshall into the struct. For example, here's a test failure in the terraform provider: https://gitlab.com/gitlab-org/terraform-provider-gitlab/-/jobs/9717240359

It's a breaking change, but presumably it's already broken? I've also added some missing fields.