Many to Many relationship - Foreign key violation. insert or update on table

### Version Information

Server Version:
CLI Version (for CLI related issue): v2.30.1

### Environment

### What is the current behaviour?

My mutation does not work after upgraded Hasura version.

```
mutation insertSaasCompany(
$company: companies_insert_input!
$isOnboarding: Boolean!
$group: groups_insert_input!
) {
insertedGroup: insert_groups_one(object: $group) @include(if: $isOnboarding) {
group_id
name
type
}
insertedCompany: insert_companies_one(object: $company) {
companyId: company_id
groupId: group_id
}
}
```

My variables
```
{
"company": {
"company_id": "8b4ac3fb-bbc1-4893-afde-bde40e042584",
...
"company_employees": {
"data": [
{
"employee_id": "cdca39a3-e7fc-49d5-ae7b-1510ece54551",
...
}
]
},
...
"expense_policies": {
"data": [
{
...,
"expense_policies_employees": {
"data": [
{
"employee_id": "cdca39a3-e7fc-49d5-ae7b-1510ece54551"
}
]
}
}
]
},
...
},
"isOnboarding": true,
...
}
```

It worked on version 2.27 and older. But I got error after upgraded version to 2.28 - 2.30.1

### Please provide any traces or logs that could help here.
```
{
"errors": [
{
"message": "Foreign key violation. insert or update on table \"expense_policies_employees\" violates foreign key constraint \"expense_policies_employees_employee_id_fkey\"",
"extensions": {
"path": "$.selectionSet.insert_companies_one.args.object[0].expense_policies.data[0].expense_policies_employees.data",
"code": "constraint-violation"
}
}
]
}
```

### Any possible solutions/workarounds you're aware of?
I think it related to this issue https://github.com/hasura/graphql-engine/issues/8522
employee_id is predefined with uuid v4()

Start by reproducing the mutation with the nested company, expense policy, and employee data on version 2.27 and versions 2.28–2.30.1, then compare the nested-insert behavior and foreign-key ordering. Done means the mutation succeeds without the expense_policies_employees_employee_id_fkey violation, or the regression is isolated to a specific change.

Written by the indexing model from the issue text.