[submodule]: update sonic-utilities

* 6ced42c 2021-03-11 | Revert "[config] Enable/disable container monitoring when starting/stopping the services. (sonic-net#1471)" (HEAD, origin/master, origin/HEAD) [Guohan Lu]
* e1c52a0 2021-03-11 | [warm-reboot]: added automated recover for ISSU file (sonic-net#1466) [Vadym Hlushko]
* a4ae643 2021-03-10 | [PDDF] Remove references to deprecated platform plugins (sonic-net#1485) [fk410167]

Signed-off-by: Guohan Lu <lguohan@gmail.com>