Internal Server Error when using Hasura Cloud GraphQL API to create cloud_free_v2 tenant with env vars

### Version Information

Server Version: N/A
CLI Version (for CLI related issue): N/A

### Environment

Cloud

### What is the current behaviour?

Tried this query:

```
mutation MyMutation {
createTenant(
cloud: "aws"
region: "eu-central-1"
envs: [{key: "HASURA_GRAPHQL_SECRET", value: "abcd"}, {key: "HASURA_GRAPHQL_DATABASE_URL", value: "abcd"}]
name: "test-personal-website-pr-2"
plan: "cloud_free_v2"
) {
tenant {
slug
}
}
}
```

It failed with

```
{
"errors": [
{
"extensions": {
"code": "GenericServerError",
"id": "59c12a95-83d6-4704-9130-3b84f38d6ed9"
},
"message": "there was an internal error while serving your request"
}
]
}
```

The tenant did get created, but the env vars were missing.

But then if I comment out the line with the env vars, it doesn't error.

### What is the expected behaviour?

it succeeds.

### How to reproduce the issue?

Run the above query in the public GraphiQL UI with a PAT pointing to `https://data.pro.hasura.io/v1/graphql`

### Screenshots or Screencast

### Please provide any traces or logs that could help here.

don't got any.

### Any possible solutions/workarounds you're aware of?

make it without the env vars and then add them later

### Keywords