[4.5][CLOUDSTACK-8649] Cherry pick fix SSH key registering

[Wido den Hollander]

Hi Rohit,

Could you cherry-pick 2e79c628e052ebdaf782458cfe4c4ef6e95545c6 into the
4.5 branch?

This is the issue: https://issues.apache.org/jira/browse/CLOUDSTACK-8649

Wido