Bump sql_database_instance create timeout from 30 to 40 minutes

[modular-magician]

Related to hashicorp/terraform-provider-google#12912

The sql_database_instance tests that run nightly will frequently fail when they hit the 30 minute timeout. It is potentially more likely for configurations that involve clones and backups, but in any case, if the resource can realistically take >30 minutes to create, then the timeout should be higher, so it is only triggered when something is wrong.

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sql: changed the default create timeout of `google_sql_database_instance` to 40m from 30m

Derived from GoogleCloudPlatform/magic-modules#7118