fix: avoid re-building when comparing two baseline results

[vsarunas]

Description

Avoid building the products when comparing 2 baselines:

swift package -c release --disable-sandbox benchmark baseline check main_1 main_2
swift package -c release --disable-sandbox benchmark baseline compare main_1 main_2

How Has This Been Tested?

Please describe the tests that you ran to verify your changes.

Minimal checklist:

• I have performed a self-review of my own code
• I have added DocC code-level documentation for any public interfaces exported by the package
• I have added unit and/or integration tests that prove my fix is effective or that my feature works

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 69.41%. Comparing base (6b8c88f) to head (3a49692).
⚠️ Report is 1 commits behind head on main.

Additional details and impacted files

@@           Coverage Diff           @@
##             main     #335   +/-   ##
=======================================
  Coverage   69.41%   69.41%           
=======================================
  Files          33       33           
  Lines        4051     4051           
=======================================
  Hits         2812     2812           
  Misses       1239     1239           

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