Unable to add skip_wait_for_deletion to an existing group service account
## Bug Report
When adding the new `skip_wait_for_deletion` attribute to a pre-existing `gitlab_group_service_account` resource, it attempts to do an update. However, all the other attributes are set to force a delete/create when changed, so the update function returns an error if it is called.
## Relevant Terraform Configuration
```hcl
resource "gitlab_group_service_account" "service_account" {
group = 123
username = "service_account_123"
}
```
Apply the resource, then change the config:
```hcl
resource "gitlab_group_service_account" "service_account" {
group = 123
username = "service_account_123"
skip_wait_for_deletion = true
}
```
## Relevant Log Output
```shell
Modifying...
╷
│ Error: Provider Error, report upstream
│
│ with gitlab_group_service_account.service_account,
│ on .terraform/gitlab_group_service_account.tf line 5, in resource "gitlab_group_service_account" "service_account":
│ 5: resource "gitlab_group_service_account" "service_account" {
│
│ Somehow the resource was requested to perform an in-place upgrade which is
│ not possible.
╵
```
</details>
## Additional Details
<!-- 🚧 Please fill in the used versions below between the backticks. -->
- GitLab Terraform Provider Version: `19.0`
- GitLab Instance Version: `19.0`
- Terraform Version: `1.15`
- License Tier: `Ultimate`
## Implementation Details
- Modify the `Update` function of the internal/provider/resource_gitlab_group_service_account.go resource to update the value of `skip_wait_for_deletion` before returning. No API calls needs to be made since this is essentially a meta-attribute.
- Create a test that creates a group_service_account with `skip_wait_for_deletion = false`, then changes it to `skip_wait_for_deletion = true` in a second step while changing nothing else. Use `plancheck.ExpectResourceAction` to check that an update is performed instead of a Replace, and then use normal resource checks to validate the group and username don't change.
issue