tiup cluster deploy: using -user instead of --user leads to misleading SSH authentication error

Bug Report

Please answer these questions before submitting your issue. Thanks!

1. What did you do?

I deployed a TiDB cluster using tiup cluster deploy, but accidentally used -user instead of --user as the flag name.

Steps to reproduce:

tiup cluster deploy tidb-ryl v8.5.3 topo.yaml -user tidb -i global_user

2. What did you expect to see?

unknown flag: -user
did you mean --user ?

3. What did you see instead?
   TiUP did not report any flag parsing error and continued execution.
   Later, it failed during the SSH phase with a misleading authentication error:

Error: failed to fetch cpu-arch or kernel-name: executor.ssh.execute_failed: Failed to execute command over SSH for 'ser@10.0.0.3:22' {ssh_stderr: , ssh_stdout: , ssh_command: export LANG=C; PATH=$PATH:/bin:/sbin:/usr/bin:/usr/sbin; /usr/bin/sudo -H bash -c "uname -m"}, cause: ssh: handshake failed: ssh: unable to authenticate, attempted methods [none publickey], no supported methods remain

4. What version of TiUP are you using (tiup --version)?
   1.16.3 tiup
   Go Version: go1.24.1
   Git Ref: v1.16.3

Start by reproducing the tiup cluster deploy command with -user instead of --user, then trace the command's argument parsing before the SSH phase. Done means the command stops immediately with an unknown-flag error that suggests --user, rather than continuing to SSH and reporting an authentication failure.