seedlink basic client, get_info(): terminate properly

[megies]

What does this PR do?

Seems seedlink basic client in get_info() did not properly signal that everything was received
and ready to terminate. not sure why it worked before..

Why was it initiated? Any relevant Issues?

tries to fix #2995

PR Checklist

• Correct base branch selected? master for new features, maintenance_... for bug fixes
• This PR is not directly related to an existing issue (which has no PR yet).
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  Just add the "build_docs" tag to this PR.
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  just add the "test_network" tag to this PR.
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[megies]

Looks like return False in packet handler keeps the low-level client expecting more packets with data in them (here, metadata on available stations as xml plain text). So when a terminated/terminating (TYPE_SLINFT: Packet type is terminated info packet.) packet is received we should return True and then the low-level continuous packet reception loop is hitting a break statement and stopping.

Not sure how this worked before..

(seiscomp has had some major version jumps since this was first implemented, probably something changed in their seedlink server implementation and before the server was just stopping by itself and now is expecting a data request after we dont terminate properly)

[megies]

@trichter ah, i should've probably added that network test label when opening the PR? 😬

[trichter]

@trichter ah, i should've probably added that network test label when opening the PR?

Just push another empty commit to trigger the tests.

[trichter]

That was a quick fix! Nice. It also reduces the spent time for network tests significantly 👍

[trichter]

Do you want to include a changelog or just merge?

[megies]

Added changelog 👍