Update conditional statements in guided_notebook_tests.yaml

[ChristianZaccaria]

The difference between these statements:

1. ${{ github.event.label.name == 'test-guided-notebooks' }}
   This job is triggered on adding the label or removing->re-adding the label. If a new change is pushed to a PR, the test will not re-run unless the label is added again.

2. ${{ contains(github.event.pull_request.labels.*.name, 'test-guided-notebooks') }}
   This job is triggered if the label is present in the PR. If a new change is pushed to a PR, the test will re-run if the label is present.

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 94.11%. Comparing base (13658b8) to head (3b131da).
Report is 3 commits behind head on main.

Additional details and impacted files

@@           Coverage Diff           @@
##             main     #743   +/-   ##
=======================================
  Coverage   94.11%   94.11%           
=======================================
  Files          36       36           
  Lines        2412     2412           
=======================================
  Hits         2270     2270           
  Misses        142      142           

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[openshift-ci]

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