Remove outdated integration test

[JostMigenda]

This fixes a minor oversight in #193 by removing a test script used to test the snewpy.snowglobes_interface.SNOwGLoBES class that was now removed. It also simplifies the GitHub integration test workflow.

[github-actions[bot]]

Result of Benchmark Tests

Benchmark	Min	Max	Mean
python/snewpy/test/test_snowglobes.py::test_simulation_chain_benchmark	5.24	5.42	5.35 +- 0.08

[mcolomermolla]

After reviewing it, I don't see any reason why this PR shouldn't be merged. The changes made are straightforward after removing globes.

[JostMigenda]

Thanks for checking @mcolomermolla!