[DOGE-105] Robustify tests

[doctrino]

Description

A few minor adjustments of tests found when setting up the contributor project.

RISK REVIEWER: Only touching tests, improving some fixtures to auto create data. -> Low risk.

Checklist:

• Tests added/updated.
• Documentation updated. Documentation is generated from docstrings - these must be updated according to your change.
  If a new method has been added it should be referenced in cognite.rst in order to generate docs based on its docstring.
• Changelog updated in CHANGELOG.md.
• Version bumped. If triggering a new release is desired, bump the version number in _version.py and pyproject.toml per semantic versioning.

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 90.38%. Comparing base (c37796e) to head (2cbdb92).
Report is 1 commits behind head on master.

Additional details and impacted files

@@            Coverage Diff             @@
##           master    #2125      +/-   ##
==========================================
+ Coverage   90.37%   90.38%   +0.01%     
==========================================
  Files         152      152              
  Lines       23127    23127              
==========================================
+ Hits        20900    20903       +3     
+ Misses       2227     2224       -3     

see 2 files with indirect coverage changes

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[larshagencognite]

Looks fine, but I would like to see the answer to @erlendvollset's comment before completing risk review.

[erlendvollset]

LGTM

[larshagencognite]

risk review ok