fixed TrimLeft usage to TrimPrefix for us to not miss characters

[itzikban]

Hi Guys,

Found an issue in Kubernetes connector that affects enumerated containers. I used TrimPrefix instead of TrimLeft function because TrimLeft has removed in some cases characters in ContainerID hash.

Here is a simple example that showcases the reason for the change: https://play.golang.org/p/B2FD7C4rpuW

[wrfly]

@itzikban thanks!