[BUG] agent execution error message

[jngz-es]

What is the bug?
Agent execution api will return the following error message if the root cause exception doesn't occur in coordinate node and is wrapped into remote transport exception.

"{\"error\":{\"reason\":\"Invalid Request\",\"details\":\"[d0aa9b912dfc3dacaf11334ad978ea34][x.x.x.x:x][cluster:admin/opensearch/ml/execute]\",\"type\":\"RemoteTransportException\"},\"status\":400}"

[yuye-aws]

This info might help you: the wrapped "so-called" remote transport exception is actually of type ResponseException