Fix NTP integration test in the case of multiple occurrences of the package

[nebeid]

Fix the NTP integration test, a continuation of the fix in #1548.

When there were multiple .tar.gz packages, the test was trying wget with

wget -q https://downloads.nwtime.org/ntp//ntp-4.2.8p17.tar.gz ntp-4.2.8p18-RC1.tar.gz

and was failing.

[codecov-commenter]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 77.90%. Comparing base (e82f824) to head (065579c).

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #1588      +/-   ##
==========================================
- Coverage   77.91%   77.90%   -0.01%     
==========================================
  Files         560      560              
  Lines       94613    94613              
  Branches    13618    13618              
==========================================
- Hits        73720    73711       -9     
- Misses      20299    20308       +9     
  Partials      594      594              

☔ View full report in Codecov by Sentry.
📢 Have feedback on the report? Share it here.

[nebeid]

Superseded by #1589