Cleanup ssh tunnels on cancel

[m-lima]

Details
In pkg/minikube/tunnel/kic/ssh_tunnel.go the interrupt signal is caught and it stops the LoadBalancerEmulator. However, it assumes that the interrupt will also propagate to the children ssh tunnels, which are running in a goroutine inside startConnections.
The interrupt, however, kills the goroutine and the blocking call which waits for the child process to finish. This leaves the ssh tunnels dangling.
On the other hand, if CTRL + C is sent on the same terminal as minikube tunnel and the clean-up routine included killing all ssh tunnels, the OS would error with "process already finished".

This leads to accumulation of processes and is likely to happen. Since minikube tunnel is a blocking command, users will tend to detach it from the terminal and kill it with a SIGINT (as proposed in #3647).

Approaches
There are two proposed approaches. This PR takes the approach of having the tunnel know if is running or not. The second approach is to have the parent of all connections managed and know which processes should be killed.

The first approach, proposed with this PR, also addresses #8511, by letting the process owner hold the knowledge if the process is running or not. Since the ssh tunnels are started inside startAndWait() on pkg/minikube/tunnel/kic/ssh_conn.go, and a blocking call to Wait() is made, the owner can know when the process is started, finished, or killed.

The second approach is more oriented towards the cleaning up of the ssh tunnels, and isolates changes to only pkg/minikube/tunnel/kic/ssh_tunnel.go. However it relies on sync. The second approach can be seen here: https://github.com/m-lima/minikube/tree/issue/10752-managed-kill

Output
With this PR, users will be notified of connections being closed (as opposed to the silent death that happens now). E.g:

$ minikube tunnel
🏃  Starting tunnel for service serviceA.
🏃  Starting tunnel for service serviceB.
🏃  Starting tunnel for service serviceC.
^C✋  Tunnel for service serviceB.
✋  Tunnel for service serviceA stopped.
✋  Tunnel for service serviceC stopped.

Also, when detaching from the terminal, all ssh tunnels will be reaped, also outputting to the terminal (if not redirected by the user). E.g:

$ minikube tunnel
🏃  Starting tunnel for service serviceA.
🏃  Starting tunnel for service serviceB.
🏃  Starting tunnel for service serviceC.

On another terminal:

kill -INT <PID>

Main terminal:

✋  Stopping tunnel for service serviceA.
✋  Stopping tunnel for service serviceB.
✋  Stopping tunnel for service serviceC.

fixes #10752

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[APPROVALNOTIFIER] This PR is NOT APPROVED

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Can one of the admins verify this patch?

[m-lima]

/check-cla

[m-lima]

/check-cla

[medyagh]

@m-lima thanks for this PR, do u mind checking if the Email u are using in the terminal is the same on that is Signed CLA in
https://identity.linuxfoundation.org/projects/cncf

[m-lima]

@m-lima thanks for this PR, do u mind checking if the Email u are using in the terminal is the same on that is Signed CLA in
https://identity.linuxfoundation.org/projects/cncf

I used my github account to sign the CLA. Got an email confirmation on my email and it all looked good.
I assume that by checking my email in the terminal, you mean to check that the commits were made with the same email that was used for CLA, right? I just double checked that and it is correct.
I assumed that the problem with the CLA not validating was because of the migration that the linux foundation was reporting..

[medyagh]

@m-lima
thats possible how rebasing the PR and force push the commits ? maybe that would help ?

[m-lima]

@m-lima
thats possible how rebasing the PR and force push the commits ? maybe that would help ?

Sure I'll try that

[m-lima]

@medyagh would it be helpful or harmful if I close this PR and try it again from scratch?