fix: wait for network idle in e2e

[LesnyRumcajs]

Summary of changes

Changes introduced in this pull request:

• This might not be the best way to fix e2e flakiness, especially if we introduce more network events to the faucet, but it resolves the e2e flakiness that we experience at the moment. A better solution might come as a follow-up.

https://grafana.com/docs/k6/latest/javascript-api/k6-browser/page/waitfornavigation/#events

Reference issue to close (if applicable)

Closes

Other information and links

Change checklist

• I have performed a self-review of my own code,
• I have made corresponding changes to the documentation. All new code
  adheres to the team's
  documentation standards,
• I have added tests that prove my fix is effective or that my feature works
  (if possible),
• I have made sure the CHANGELOG is up-to-date. All user-facing changes
  should be reflected in this document.

[codecov-commenter]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 18.03%. Comparing base (997dc9a) to head (912075f).

Additional details and impacted files

@@           Coverage Diff           @@
##             main     #255   +/-   ##
=======================================
  Coverage   18.03%   18.03%           
=======================================
  Files          39       39           
  Lines        2085     2085           
=======================================
  Hits          376      376           
  Misses       1709     1709           

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