fix(network): don't disable cache for auth challenge

[Androbin]

#729 introduced _updateProtocolRequestInterception
Objective: Call Network.setRequestInterceptionEnabled for auth challenge or if requested by user

#1154 introduced Network.setCacheDisabled
Objective: Ensure custom user response handling is always called

#4260 introduced _updateProtocolCacheDisabled
Objective: Call Network.setCacheDisabled if requested by user

The cache and request interception work on the network level, while we want the custom user response handling to work independent of the network, which is why we're currently forced to disable the cache in some cases.

As long as there is no custom user response handling, it should be unnecessary to disable the cache for the auth challenge, since it only needs to be called in case of an actual network request anyway.

Related issue: #2905

[mathiasbynens]

@OrKoN could you PTAL?

[OrKoN]

The change LGTM. It seems there are no current tests for this logic. Would it be possible to add the tests so that we capture the right expectations and no one changes the logic back if it does not work for some use cases?

[Androbin]

@OrKoN I added a unit test covering this logic.

[OrKoN]

Thanks!

[Androbin]

Related: #6996, #7038, and #7060