Support to select DNS upstreams randomly or by round-robin

[PeterDaveHello]

Prerequisites

• [x] I am running the latest version
• [x] I checked the documentation and found no answer
• [x] I checked to make sure that this issue has not already been filed

Feature Description

Allow AdGuard to select upstream DNS servers randomly(not weighted)

Proposed Solution

Add another strategy option besides current load-balancing, parallel requests and fastest IP address.

Additional Information

That's something supported in dnscrypt-proxy and blocky, not sure if you'd also consider to support it in AdGuard Home? Thanks ;)

[fonic]

I second this. Random or round-robin would be a really nice feature in terms of privacy. Also, the current weighted approach often results in a single fast provider in the list being used for almost all requests.

[hnry]

I second this. Random or round-robin would be a really nice feature in terms of privacy. Also, the current weighted approach often results in a single fast provider in the list being used for almost all requests.

I'm glad someone pointed this out. This isn't what I expected a weighted load balance to do. It completely favors a single upstream (we're talking 99%+). See https://github.com/AdguardTeam/AdGuardHome/discussions/6361 , https://github.com/AdguardTeam/AdGuardHome/issues/3521

[fonic]

I'm glad someone pointed this out. This isn't what I expected a weighted load balance to do. It completely favors a single upstream (we're talking 99%+). See #6361 , #3521

Even worse, it seems to randomly favor a single upstream provider for a certain amount of time. With 8 providers in the list, whenever I check the dashboard, one provider is apparently being used for >98% of all request, but it's not always the same one (changes over a couple of days).

[DonPablo1010]

I support this concern. An additional option with Round Robin would make Unbound unnecessary for me in the upstream. That would be great!