feat(cli-test): include expected test trace outputs for the "env" subcommands

[zimeg]

Summary

This PR adds the expected test trace outputs for the env command.

These are labelled as "variables" to match internal CLI structure - var is an alias of env - but that can be updated!

Requirements

• I've read and understood the Contributing Guidelines and have done my best effort to follow them.
• I've read and agree to the Code of Conduct.

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 91.66%. Comparing base (278514f) to head (dff7839).
Report is 3 commits behind head on main.

Additional details and impacted files

@@           Coverage Diff           @@
##             main    #2097   +/-   ##
=======================================
  Coverage   91.65%   91.66%           
=======================================
  Files          38       38           
  Lines       10311    10315    +4     
  Branches      647      647           
=======================================
+ Hits         9451     9455    +4     
  Misses        848      848           
  Partials       12       12           

Flag	Coverage Δ
cli-hooks	95.23% <ø> (ø)
cli-test	94.48% <100.00%> (+0.01%)	⬆️
oauth	77.39% <ø> (ø)
socket-mode	58.22% <ø> (ø)
web-api	96.88% <ø> (ø)
webhook	96.65% <ø> (ø)

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[mwbrooks]

👌🏻

[zimeg]

@filmaj @mwbrooks Thank y'all both for the reviews! This is set to land in the next CLI release, so I think it's alright to merge now and tag later.

I plan to follow up with this and perhaps a few other changes to @slack/cli-test in neartimes 👁️‍🗨️