test: fix nodepool e2e test

[tnsimon]

What type of PR is this?

/kind enhancement

What this PR does / why we need it:

Fixes the nodepool e2e test which is currently commented out

Which issue(s) this PR fixes:

Fixes #2282

Special notes for your reviewer:

/assign @rambohe-ch

Does this PR introduce a user-facing change?

no

other Note

In the e2e test, worker2 is not assigned to anything; we instead evaluate 2 scenarios:

1. Create an empty nodepool without nodes then delete it (this is allowed as the webhook won't return validation error).
2. Create a nodepool with worker2 (currently unmapped). Assert it became ready in the nodepool. We don't delete this as there's no simple way to recreate it in the kind cluster (for now).

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 46.40%. Comparing base (d690808) to head (c1278de).
Report is 1 commits behind head on master.

Additional details and impacted files

@@           Coverage Diff           @@
##           master    #2283   +/-   ##
=======================================
  Coverage   46.39%   46.40%           
=======================================
  Files         416      416           
  Lines       27266    27266           
=======================================
+ Hits        12651    12653    +2     
+ Misses      13335    13333    -2     
  Partials     1280     1280           

Flag	Coverage Δ
unittests	46.40% <ø> (+<0.01%)	⬆️

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[sonarqubecloud]

Quality Gate passed

Issues
1 New issue
0 Accepted issues

Measures
0 Security Hotspots
0.0% Coverage on New Code
0.0% Duplication on New Code

See analysis details on SonarQube Cloud

[rambohe-ch]

/LGTM