[_shard] use absolute imports for ShardMetadata instead (#73678)
Summary:
Pull Request resolved: https://github.com/pytorch/pytorch/pull/73678
quick fix to use absolute imports instead of relative imports
ghstack-source-id: 150346661
Test Plan: wait for ci
Reviewed By: pritamdamania87
Differential Revision: D34587342
fbshipit-source-id: b7c3fc91dff5fc5cbd88e91894f1d4a80e4a5493
(cherry picked from commit 23753e703400e6fa5ae2dc03e7275f0a95d18721)
