Use Webpack plugin example Snap for testing updates

[Mrtenz]

Bumping the BIP-32 example in #3185 caused issues in the MetaMask extension E2E tests. We don't update the Webpack plugin example so often, and it's not on the test-snaps page directly, so less likely to cause issues in the future.

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 94.93%. Comparing base (2aadca0) to head (a5b0c6e).
Report is 1 commits behind head on main.

Additional details and impacted files

@@           Coverage Diff           @@
##             main    #3186   +/-   ##
=======================================
  Coverage   94.93%   94.93%           
=======================================
  Files         507      507           
  Lines       11184    11184           
  Branches     1722     1722           
=======================================
  Hits        10618    10618           
  Misses        566      566           

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