feat: refactor testing (#35)

## Description

<!-- **Please link some issue here describing what you are trying to achieve.**

In case there is no issue present for your PR, please consider creating one.
At least please give us some description what you are trying to achieve and why your change is needed. -->

relates to #1234

## Checklist

- [ ] Issue was linked above
- [ ] Code format was applied: `make fmt`
- [ ] Examples were added / adjusted (see `examples/` directory)
- [x] Docs are up-to-date: `make generate-docs` (will be checked by CI)
- [ ] Unit tests got implemented or updated
- [ ] Acceptance tests got implemented or updated (see e.g. [here](f5f99d1709/stackit/internal/services/dns/dns_acc_test.go))
- [x] Unit tests are passing: `make test` (will be checked by CI)
- [x] No linter issues: `make lint` (will be checked by CI)

Reviewed-on: #35
Reviewed-by: Andre_Harms <andre.harms@stackit.cloud>
Co-authored-by: Marcel S. Henselin <marcel.henselin@stackit.cloud>
Co-committed-by: Marcel S. Henselin <marcel.henselin@stackit.cloud>

stackit/internal/wait/sqlserverflexbeta/wait.go

@@ -96,7 +96,7 @@ func UpdateInstanceWaitHandler(ctx context.Context, a APIClientInterface, projec
 			tflog.Info(ctx, "request is being handled", map[string]interface{}{
 				"status": *s.Status,
 			})
-			return false, nil, nil
+			return false, s, nil
 		default:
 			tflog.Info(ctx, "Wait (update) received unknown status", map[string]interface{}{
 				"instanceId": instanceId,
@@ -105,17 +105,15 @@ func UpdateInstanceWaitHandler(ctx context.Context, a APIClientInterface, projec
 			return false, s, nil
 		}
 	})
-	handler.SetSleepBeforeWait(15 * time.Second)
-	handler.SetTimeout(45 * time.Minute)
 	return handler
 }
 
 // DeleteInstanceWaitHandler will wait for instance deletion
-func DeleteInstanceWaitHandler(ctx context.Context, a APIClientInterface, projectId, instanceId, region string) *wait.AsyncActionHandler[struct{}] {
-	handler := wait.New(func() (waitFinished bool, response *struct{}, err error) {
-		_, err = a.GetInstanceRequestExecute(ctx, projectId, region, instanceId)
+func DeleteInstanceWaitHandler(ctx context.Context, a APIClientInterface, projectId, instanceId, region string) *wait.AsyncActionHandler[sqlserverflex.GetInstanceResponse] {
+	handler := wait.New(func() (waitFinished bool, response *sqlserverflex.GetInstanceResponse, err error) {
+		s, err := a.GetInstanceRequestExecute(ctx, projectId, region, instanceId)
 		if err == nil {
-			return false, nil, nil
+			return false, s, nil
 		}
 		var oapiErr *oapierror.GenericOpenAPIError
 		ok := errors.As(err, &oapiErr)
@@ -127,7 +125,7 @@ func DeleteInstanceWaitHandler(ctx context.Context, a APIClientInterface, projec
 		}
 		return true, nil, nil
 	})
-	handler.SetTimeout(15 * time.Minute)
+	handler.SetTimeout(30 * time.Minute)
 	return handler
 }