Update magic_wan_ipsec_tunnel.md

[akfroman]

Documentation shows health_check_enabled default as true, but in my testing, the default is actually false

[github-actions]

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[jacobbednarz]

thanks for the PR! unfortunately, the file you've edited is a generated artifact of the documentation process. to see how to make changes to the documentation, you're best to check out https://github.com/cloudflare/terraform-provider-cloudflare/blob/master/contributing/registry-documentation.md