Remove duplicate answers in DNS queries

[sujaldev]

Description

Fixes #6647 by assuming all DNS queries are made over UDP, will need to be reworked when TCP support is added.

Checklist

• I have updated tests where applicable.
• I have added an entry to the CHANGELOG.

[meitinger]

Good catch and thanks for the PR.

LGTM, but it shouldn't matter what value we use in the type param (as long as it's DGRAM or STREAM). If anything, we need to query/reflect the type of the upstream connection, not whether DNS answers via UDP or TCP.
Perhaps we should therefore just specify SOCK_STREAM, since it's usage for upstream endpoints is more likely as of today in mitmproxy. (But again, I don't know of any kconfig, sysctl, gai.conf or resolv.conf flags, that would allow only one of UDP and TCP but not the other.)

[mhils]

@meitinger: approver merges :)