fix ssh Operation timed out

[tedteng]

Describe the bug
SSH gardener@18.159.92.22 => gardener@ip-10-250-7-211.eu-central-1.compute.internal
Connection closed by 18.159.92.22 port 22

the SSH ConnectionAttempts retry seems scope on bastion => node , not user => bastion

To Reproduce
Steps to reproduce the behavior:

1. 'gardenctl ssh node'

Expected behavior

Screenshots
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Gardenctl Version (please complete the following information):

gardenctl:
		version     : v0.19.0
		build date  : 2020-07-30
		go version  : go1.13.4
		go compiler : gc
		platform    : darwin/amd64

Additional context
Add any other context about the problem here.

[tedteng]

/assign