fix(api): correctly handle organization_id on creation (#11396)

# Which Problems Are Solved

While moving the some requests from the v2beta organization service to
v2, the `org_id` property of the `AddOrganization` request was
deprecated in favor of `organization_id`. However, the internal logic
was adjusted, resulting in a ingored `organization_id`.

# How the Problems Are Solved

- properly favor `organization_id` over `org_id` and added a note to the
proto.

# Additional Changes

none

# Additional Context

- closes #11269
- requires backport to v4.x

internal/api/grpc/org/v2/integration_test/org_test.go

@@ -96,6 +96,31 @@ func TestServer_AddOrganization(t *testing.T) {
 				CreatedAdmins:  []*org.AddOrganizationResponse_CreatedAdmin{},
 			},
 		},
+		{
+			name: "no admin, custom organization ID",
+			ctx:  CTX,
+			req: &org.AddOrganizationRequest{
+				Name:           integration.OrganizationName(),
+				OrganizationId: gu.Ptr("custom-organization-ID"),
+			},
+			want: &org.AddOrganizationResponse{
+				OrganizationId: "custom-organization-ID",
+				CreatedAdmins:  []*org.AddOrganizationResponse_CreatedAdmin{},
+			},
+		},
+		{
+			name: "no admin, custom organization ID (precedence over org ID)",
+			ctx:  CTX,
+			req: &org.AddOrganizationRequest{
+				Name:           integration.OrganizationName(),
+				OrganizationId: gu.Ptr("custom-organization-ID2"),
+				OrgId:          gu.Ptr("custom-org-ID"), // will be ignored in favor of OrganizationId
+			},
+			want: &org.AddOrganizationResponse{
+				OrganizationId: "custom-organization-ID2",
+				CreatedAdmins:  []*org.AddOrganizationResponse_CreatedAdmin{},
+			},
+		},
 		{
 			name: "admin with init with userID passed for Human admin",
 			ctx:  CTX,