TepCommandHelper exceptions should not be caught and should be propagated

https://git.opendaylight.org/gerrit/#/c/74602/ has introduced RetryingManagedTransactionRunner in TepCommandHelper, and some usages of the same have been changed to catch the exceptions thrown. Propagating the exception was requiring an API change, and hence, has not been done for Oxygen.

This Jira is to track a cleaner implementation, by properly propagating the exceptions.