Populate After.ServerVersion on StopReplicationAndGetStatus success path

The successful stop path set Before.ServerVersion but left After.ServerVersion
empty, while the no-op paths return After: before and thus include it. Set
after.ServerVersion = before.ServerVersion so the common success path is
consistent, and extend the test to assert After.ServerVersion when present.

Co-Authored-By: Claude <svc-devxp-claude@slack-corp.com>
Signed-off-by: Eduardo Ortega <5791035+ejortegau@users.noreply.github.com>

Author: ejortegau

go/vt/vttablet/tabletmanager/rpc_replication.go

@@ -1086,6 +1086,7 @@ func (tm *TabletManager) StopReplicationAndGetStatus(ctx context.Context, stopRe
 	rs.RelayLogSourceBinlogEquivalentPosition = rsAfter.RelayLogSourceBinlogEquivalentPosition
 
 	before.ServerVersion = tm.getMySQLVersion(ctx)
+	after.ServerVersion = before.ServerVersion
 
 	return StopReplicationAndGetStatusResponse{
 		Status: &replicationdatapb.StopReplicationStatus{

go/vt/vttablet/tabletmanager/rpc_replication_test.go

@@ -876,6 +876,9 @@ func TestStopReplicationAndGetStatus_ServerVersion(t *testing.T) {
 
 			require.NotNil(t, resp.Status)
 			require.Equal(t, "Ver 8.0.35", resp.Status.Before.ServerVersion)
+			if resp.Status.After != nil {
+				require.Equal(t, "Ver 8.0.35", resp.Status.After.ServerVersion)
+			}
 		})
 	}
 }