Update tests prebuilt asserters

[jakubmajercik]

Changelog

Tests for components under multiomics/process_samples updated with prebuilt asserters, synthetic data and pytest fixtures

Issue ticket number and link

Closes #734

Checklist before requesting a review

• [x] I have performed a self-review of my code

• [x] Conforms to the Contributor's guide

• Check the correct box. Does this PR contain:

  • [ ] Breaking changes
  • [ ] New functionality
  • [ ] Major changes
  • [x] Minor changes
  • [ ] Documentation
  • [ ] Bug fixes

• [x] Proposed changes are described in the CHANGELOG.md

• [ ] CI tests succeed!