Allow Cloud SQL deletion

[e-koma]

What Pull Reqeust

parameterized Cloud SQL's deletion_protection.

Why

Cloud SQL( google_sql_database_instance ) is default deletion_protection = "true", which makes it impossible to destroy terraform. I actually encountered the following situations.

1. terraform apply fails when Cloud SQL's destructive parameters are set.
2. In the situation like forseti setting did not works well(Cloud SQL starts, but GKE does not start well), I want to delete Cloud SQL, but cannot delete it.
3. even if we want to run forseti as a trial, but after trying, we cannot delete Cloud SQL.

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[e-koma]

@googlebot I signed it!

[e-koma]

I now understand this issue cause terraform-provider-google version is above 3.44 in my local environment.

deletion_protection option is set by default true after google provider version 3.44, and cannot delete it. https://github.com/hashicorp/terraform-provider-google/blob/master/CHANGELOG.md#3440-october-19-2020

but forseti examples google provider are below 3.44. So this issue is not relevant in the current forseti's google provider version. I'm going to rewrite my local configuration to run it.

Thank you for your patience.