Stop showing debug logs during fleetctl preview, slight reformat

[dantecatalfamo]

Related issue: #32208

• Changes file added for user-visible changes in changes/, orbit/changes/ or ee/fleetd-chrome/changes.
  See Changes files for more information.

Testing

• QA'd all new/changed functionality manually

Also added a spinner while waiting for docker compose to start and stop, added some spacing around the login information, and bolded the username and password.

[codecov]

Codecov Report

❌ Patch coverage is 78.12500% with 7 lines in your changes missing coverage. Please review.
✅ Project coverage is 64.08%. Comparing base (11fa6ff) to head (0e1688d).
⚠️ Report is 8 commits behind head on main.

Files with missing lines	Patch %	Lines
cmd/fleetctl/fleetctl/preview.go	78.12%	4 Missing and 3 partials ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main   #33352      +/-   ##
==========================================
- Coverage   64.08%   64.08%   -0.01%     
==========================================
  Files        2061     2061              
  Lines      205110   205176      +66     
  Branches     6677     6677              
==========================================
+ Hits       131438   131479      +41     
- Misses      63306    63326      +20     
- Partials    10366    10371       +5     

Flag	Coverage Δ
backend	65.20% <78.12%> (-0.01%)	⬇️

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[sgress454]

fancy