Fix another very tricky bug related to web_connectivity 0.5 DNS mapping

[hellais]

The transaction_id is what identifies a single connection to an endpoint, so when we know it, every observation of that connection shares it. In these cases matching against the IP address is wrong, since an endpoint might be reached on the same IP multiple times (eg. once over port 80 and twice over 443 in the case of web_connectivity 0.5), so matching only on the address will mix together observations that are for different connections.

DNS queries also carry a transaction_id, but it doesn't necessarily identify the connections which follow. The web_connectivity 0.5 spec says that it SHOULD use a different ID space than connections, while other nettests the whole transaction including the query might share the same ID.
Callers mapping a DNS observation onto TCP and TLS should pass is_connection_transaction_id=False, so that the ID is only used when it actually matches, and the connection is identified via the address otherwise.

related to: #180

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 83.55%. Comparing base (c8fcc72) to head (ea61607).

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #181      +/-   ##
==========================================
+ Coverage   77.87%   83.55%   +5.67%     
==========================================
  Files          33       89      +56     
  Lines        1939     5892    +3953     
==========================================
+ Hits         1510     4923    +3413     
- Misses        429      969     +540     

Flag	Coverage Δ
oonidata	77.87% <ø> (ø)
oonipipeline	86.33% <ø> (?)

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