ssh-proxy: attach correct user for host ssh config

[tmonty12]

For Launchpad, the host user is nvidia. This wasn't being properly updated in the ssh config because it uses the ssh proxy which referenced the user variable defined by GetSSHUser not GetHostSSHUser.

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 13.25%. Comparing base (e28b4e5) to head (f4de46a).
Report is 42 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #212      +/-   ##
==========================================
+ Coverage   12.65%   13.25%   +0.60%     
==========================================
  Files          80      106      +26     
  Lines       11207    12604    +1397     
==========================================
+ Hits         1418     1671     +253     
- Misses       9590    10705    +1115     
- Partials      199      228      +29     

Flag	Coverage Δ
Linux	13.25% <100.00%> (+0.60%)	⬆️

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