[jit][perf] Reduce lookupInModule overhead. (#119145)
It's inefficient to split remaining parts of the module name by '.' just to join it back again. Instead it's more idiomatic and efficient to use `maxsplit=1` to ensure that all remaining parts remain intact. This improves best case time and space complexity since scan can terminate on first encountered `.` and only 2 parts are returned in a list.
Pull Request resolved: https://github.com/pytorch/pytorch/pull/119145
Approved by: https://github.com/Skylion007
