* gtest: add scatter to combined calls and use loops
* gtest: run validation inside loop
* gtest: revert small element count to 2520
* gtest: fix memory leak in validation
(cherry picked from commit b0853ccd51)
* Fix combined call UT
* Fix memory leak
* Fix alltoallv test
* Add alltoallv API and implementation
* Extend Rome P2P channel limit to multinode and alltoall kernels
* topo_expl: fix compilation and sync up with main
* gtest: use RCCL alltoallv API
* Code review changes
Wenkai Du
Wenkai Du