[Bug]: [CLI] dstack apply --ssh-identity is broken #4190

$ dstack apply --ssh-identity does-not-exist
Traceback (most recent call last):
<...>
FileNotFoundError: [Errno 2] No such file or directory: 'does-not-exist.pub'

$ ssh-keygen -f ~/.ssh/test_key
$ rm ~/.ssh/test_key.pub
$ dstack apply --ssh-identity ~/.ssh/test_key
Traceback (most recent call last):
<...>
FileNotFoundError: [Errno 2] No such file or directory: '/home/def/.ssh/test_key.pub'

$ dstack apply --ssh-identity ~/.ssh/test_key
<...>
task provisioning completed (running)
debian@192.168.122.75's password: [11:58:28] DEBUG    dstack._internal.core.services.ssh.tunnel:198 SSH tunnel to root@task did not open in 15 seconds
debian@192.168.122.75's password: [11:58:44] DEBUG    dstack._internal.core.services.ssh.tunnel:198 SSH tunnel to root@task did not open in 15 seconds
debian@192.168.122.75's password: [11:59:00] DEBUG    dstack._internal.core.services.ssh.tunnel:198 SSH tunnel to root@task did not open in 15 seconds
debian@192.168.122.75's password: [11:59:16] DEBUG    dstack._internal.core.services.ssh.tunnel:198 SSH tunnel to root@task did not open in 15 seconds

$ cat ~/.dstack/ssh/config
Host task-host
    HostName 192.168.122.75
    Port 22
    User debian
    IdentityFile ~/.dstack/ssh/id_rsa
    IdentitiesOnly yes
    StrictHostKeyChecking no
    UserKnownHostsFile /dev/null
Host task
    HostName localhost
    Port 32778
    User root
    IdentityFile ~/.dstack/ssh/id_rsa
    IdentitiesOnly yes
    StrictHostKeyChecking no
    UserKnownHostsFile /dev/null
    ProxyJump task-host

$ dstack apply --ssh-identity ~/.ssh/test_key
<...>
task provisioning completed (running)
User SSH key doesn't match; default SSH key (/home/def/.dstack/ssh/id_rsa) doesn't exist