remove support for dvc machine

[pmrowla]

• ❗ I have followed the Contributing to DVC checklist.

• 📖 If this PR requires documentation updates, I have created a separate PR (or issue, at least) in dvc.org and linked it here.

Thank you for the contribution - we'll try to review it as soon as possible. 🙏

Closes #9792

Since we are not using dvc machine we can just drop it from DVC for now so we don't have to maintain dead code and so we can remove the dependency on TPI/terraform

• Removes dvc.machine
• Removes dvc.repo.experiments.executor.ssh

[codecov]

Codecov Report

Patch coverage has no change and project coverage change: +0.40% 🎉

Comparison is base (bee04c6) 90.41% compared to head (f685785) 90.81%.

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #9837      +/-   ##
==========================================
+ Coverage   90.41%   90.81%   +0.40%     
==========================================
  Files         484      473      -11     
  Lines       36915    35982     -933     
  Branches     5330     5189     -141     
==========================================
- Hits        33375    32678     -697     
+ Misses       2930     2713     -217     
+ Partials      610      591      -19     

Files Changed	Coverage Δ
dvc/cli/parser.py	100.00% <ø> (ø)
dvc/commands/experiments/run.py	100.00% <ø> (ø)
dvc/repo/__init__.py	94.94% <ø> (+0.42%)	⬆️
dvc/repo/experiments/__init__.py	79.20% <ø> (-0.10%)	⬇️
tests/unit/command/test_experiments.py	100.00% <ø> (ø)

... and 3 files with indirect coverage changes

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[skshetry]

Thanks @pmrowla. I think we can also remove ./tests/remotes.