Revert the value returned from getMaxGridSize

The new value is not correct, it breaks e.g. ParallelFor2D and
ParallelFor3D (for which we had disabled tests by mistake). We need to
separate the max values for x, y and z axes, see the linked Gitlab
issue.

This reverts the commit 37632fd9

src/TNL/Cuda/LaunchHelpers.h

@@ -15,9 +15,11 @@
 namespace TNL {
 namespace Cuda {
 
-inline constexpr size_t getMaxGridSize()
+// TODO: the max grid size depends on the axis: (x,y,z): (2147483647, 65535, 65535)
+// see https://mmg-gitlab.fjfi.cvut.cz/gitlab/tnl/tnl-dev/-/issues/4
+inline constexpr std::size_t getMaxGridSize()
 {
-   return 2147483647;//65535;
+   return 65535;
 }
 
 inline constexpr int getMaxBlockSize()