fix(ci): e2e nested bootstrap cluster add d8 v ssh timeout (#2301)

Description
Add SSH keepalive options to d8 v ssh calls used in nested-cluster CI and the e2e d8 helper.
This keeps long-lived SSH sessions more stable when the VM connection is proxied through virtualization-api port-forwarding.
The following SSH options were added:

ServerAliveInterval=15 to send periodic keepalive probes during long-running sessions.
ServerAliveCountMax=8 to tolerate short interruptions before the SSH client gives up.
ConnectTimeout=10 to fail stalled connection attempts quickly and avoid hanging retries.

---------

Signed-off-by: Nikita Korolev <nikita.korolev@flant.com>

Author: universal-itengineer

.github/workflows/e2e-reusable-pipeline.yml

@@ -316,6 +316,9 @@ jobs:
             --local-ssh=true \
             --local-ssh-opts="-o StrictHostKeyChecking=no" \
             --local-ssh-opts="-o UserKnownHostsFile=/dev/null" \
+            --local-ssh-opts="-o ServerAliveInterval=15" \
+            --local-ssh-opts="-o ServerAliveCountMax=8" \
+            --local-ssh-opts="-o ConnectTimeout=10" \
             ${DEFAULT_USER}@${host}.${NAMESPACE} \
             -c "$cmd"
           }
@@ -363,6 +366,9 @@ jobs:
             --local-ssh=true \
             --local-ssh-opts="-o StrictHostKeyChecking=no" \
             --local-ssh-opts="-o UserKnownHostsFile=/dev/null" \
+            --local-ssh-opts="-o ServerAliveInterval=15" \
+            --local-ssh-opts="-o ServerAliveCountMax=8" \
+            --local-ssh-opts="-o ConnectTimeout=10" \
             ${DEFAULT_USER}@${nested_master}.${NAMESPACE} \
             -c "$cmd"
           }

test/e2e/internal/d8/d8.go

@@ -101,7 +101,7 @@ func (v D8VirtualizationCMD) SSHCommand(vmName, command string, opts SSHOptions)
 	}
 
 	localSSHOpts := "--local-ssh-opts='-o StrictHostKeyChecking=no' --local-ssh-opts='-o UserKnownHostsFile=/dev/null' --local-ssh-opts='-o LogLevel=ERROR'"
-	localSSHOpts = fmt.Sprintf("%s --local-ssh-opts='-o ConnectTimeout=%s'", localSSHOpts, timeout.String())
+	localSSHOpts = fmt.Sprintf("%s --local-ssh-opts='-o ServerAliveInterval=15' --local-ssh-opts='-o ServerAliveCountMax=8' --local-ssh-opts='-o ConnectTimeout=10'", localSSHOpts)
 
 	cmd := fmt.Sprintf("%s ssh %s -c '%s' --local-ssh=true %s", v.cmd, vmName, command, localSSHOpts)
 	cmd = v.addNamespace(cmd, opts.Namespace)