[Enhancement] Allow detach on the local docker container (#866)

*Issue #, if available:*

*Description of changes:*

* Change the default option for the local container to detach the
container so local user can start local job without rewrite the command

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docker/local/Dockerfile.local

@@ -106,5 +106,4 @@ COPY code/tools /graphstorm/tools
 COPY code/training_scripts /graphstorm/training_scripts
 COPY code/fetch_and_run.sh /graphstorm/fetch_and_run.sh
 
-
-CMD ["bash", "/graphstorm/fetch_and_run.sh"]
+CMD ["/usr/sbin/sshd", "-D"]