* Sync parmetis_wrapper with changes in metadata.json
1. In the preprocess.py, make sure that num_partitions is defined as input argument. Also, align 'input_dir' with the input dataset. schema_file is assumed to be located inside the input_dir. Also, graph_stats.txt file is assumed to be present in the input_dir.
2. Use DGL_HOME environment variable so that parmetis_wrapper command can be run anywhere.
* Fix CI test failure cases.
* Addressing CI review comments.
* Addressing CI test failures.
* Applying lintrunner patch
kylasa