E2E Tests Fail Spontaneously

[garrettmflynn]

The new end-to-end testing workflow spontaneously fails on a subset of the CI platforms for no predictable reason.

E.g. https://github.com/NeurodataWithoutBorders/nwb-guide/actions/runs/7879423399/attempts/1?pr=612 failed on Mac because of a timeout issue on the Subject page, whereas Windows failed because of the inability to locate a certain DANDI asset (whose URL appeared to have an extra colon at the end).

To Reproduce
Steps that leads to the issue:

1. Create a new branch from main
2. Submit a PR
3. Observe the Actions workflow, specifically the backend tests
4. Repeat backend tests until failure

[CodyCBakerPhD]

@garrettmflynn This seems very stable now, thanks