rec: use a more generous timeout for a test using external servers

[omoerbeek]

Other tests using external servers already use 5s

Should fix #14829 in many cases.

Short description

Checklist

I have:

• [X] read the CONTRIBUTING.md document
• [ ] compiled this code
• [ ] tested this code
• [ ] included documentation (including possible behaviour changes)
• [ ] documented the code
• [ ] added or modified regression test(s)
• [ ] added or modified unit test(s)
• [ ] checked that this code was merged to master

[coveralls]

Pull Request Test Coverage Report for Build 11704891741

Details

• 0 of 0 changed or added relevant lines in 0 files are covered.
• 112 unchanged lines in 15 files lost coverage.
• Overall coverage decreased (-0.04%) to 64.656%

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Files with Coverage Reduction	New Missed Lines	%
pdns/dnsdistdist/dnsdist-backend.cc	1	64.94%
pdns/recursordist/recursor_cache.cc	1	84.2%
pdns/recursordist/sortlist.cc	2	72.94%
pdns/recursordist/test-syncres_cc2.cc	3	88.91%
pdns/axfr-retriever.cc	3	67.89%
pdns/remote_logger.cc	3	54.71%
pdns/misc.cc	3	63.66%
pdns/iputils.cc	3	54.99%
pdns/recursordist/recpacketcache.hh	3	89.55%
pdns/recursordist/syncres.cc	6	79.56%
<!--	Total:	112		-->

Totals
Change from base Build 11703802105:	-0.04%
Covered Lines:	125703
Relevant Lines:	163573

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💛 - Coveralls