Pull request 331: Fix intermittent DoQ errors due to incorrect handling of dead cached QUIC connections

Merge in GO/dnsproxy from fix-389-doq to master

Closes #331

Squashed commit of the following:

commit d6b02d862112adc662d65dc67c90ded545672f82
Merge: a7734d8c 1b1db5ba
Author: Andrey Meshkov <am@adguard.com>
Date:   Wed May 8 22:34:40 2024 +0300

    Merge branch 'master' into fix-389-doq

commit a7734d8c
Author: Andrey Meshkov <am@adguard.com>
Date:   Sat Apr 27 18:32:35 2024 +0300

    resolve review comments

commit 419dcd29
Author: Andrey Meshkov <am@adguard.com>
Date:   Sat Apr 27 18:01:39 2024 +0300

    resolve review comments

commit 5ec92071
Author: Andrey Meshkov <am@adguard.com>
Date:   Sat Apr 27 17:58:55 2024 +0300

    resolve review comments

commit 075a44c9
Merge: 9f735799 e35720fc
Author: Andrey Meshkov <am@adguard.com>
Date:   Sat Apr 27 17:39:10 2024 +0300

    merge with master

commit 9f735799
Author: Andrey Meshkov <am@adguard.com>
Date:   Sun Mar 24 23:52:40 2024 +0300

    fix comment

commit 412e684a
Merge: 60b21f00 1b677002
Author: Andrey Meshkov <am@adguard.com>
Date:   Sun Mar 24 23:47:38 2024 +0300

    Merge branch 'master' into fix-389-doq

commit 60b21f00
Author: Andrey Meshkov <am@adguard.com>
Date:   Sun Mar 24 23:47:20 2024 +0300

    upstream: fix #389, handle quic conn errors better

commit 0dbc5e83
Author: Andrey Meshkov <am@adguard.com>
Date:   Sun Mar 24 23:20:00 2024 +0300

    upstream: add test to demonstrate #389