Need an e2e test for nydus integrated with p2p

[sctb512]

We should add an e2e test for nydus integrated with p2p, which includes the following cases:

1. p2p is the only mirror and does not work, fall back to the original registry.
2. p2p is the only mirror and works, all is well.
3. p2p is not the only mirror and does not work, try the next mirror.
4. p2p is the only mirror and auth_through is true, unauthorized requests are sent to the p2p server.
5. A normal registry is the only mirror(auth_through must be true).

[changweige]

Thanks for considering this. Frankly speaking, the test for it is fragile.

[adamqqqplay]

Currently, we do have some tests in https://github.com/dragonflyoss/Dragonfly2/actions/workflows/nydus-e2e.yml, but adding more tests would be good.