Shell executor logs through testing.T in upgrade tests

[houshengbo]

This PR is the replacement of #1598

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Comparison is base (df123ee) 79.37% compared to head (9014e75) 79.37%.
Report is 1 commits behind head on main.

Additional details and impacted files

@@           Coverage Diff           @@
##             main    #1698   +/-   ##
=======================================
  Coverage   79.37%   79.37%           
=======================================
  Files          41       41           
  Lines        1857     1857           
=======================================
  Hits         1474     1474           
  Misses        279      279           
  Partials      104      104           

☔ View full report in Codecov by Sentry.
📢 Have feedback on the report? Share it here.

[dprotaso]

/lgtm
/approve

[knative-prow]

[APPROVALNOTIFIER] This PR is APPROVED

This pull-request has been approved by: dprotaso, houshengbo

The full list of commands accepted by this bot can be found here.

The pull request process is described here

Needs approval from an approver in each of these files:

• OWNERS [dprotaso,houshengbo]

Approvers can indicate their approval by writing /approve in a comment
Approvers can cancel approval by writing /approve cancel in a comment