jobs/ttcn3-testsuites: centos: use osmocom mirror

Lately we've been seeing a lot of build failures from the TTCN3-centos
jobs running against the nightly repository. It seems that the mirror we
get redirected to isn't syncing properly. Use the Osmocom mirror
instead.

Fix for:
  Nightly packages of the Osmocom project (CentOS 190 kB/s | 1.7 kB     00:00
  Nightly packages of the Osmocom project (CentOS 1.8 kB/s | 634  B     00:00
  [91mErrors during downloading metadata for repository 'network_osmocom_nightly':
    - Status code: 404 for http://ftp.gwdg.de/pub/opensuse/repositories/network:/osmocom:/nightly/CentOS_8/repodata/7062058d3e5395b4b02570496e41e19e8fd306f5234003a6c3595331cf3fc100-filelists.xml.gz (IP: 134.76.12.6)
    - Status code: 404 for http://ftp.gwdg.de/pub/opensuse/repositories/network:/osmocom:/nightly/CentOS_8/repodata/ad91db8cb7273beaefca0e473d9c4dd12d12786819947d9abc971661c588e8c6-primary.xml.gz (IP: 134.76.12.6)
  [0m[91mError: Failed to download metadata for repo 'network_osmocom_nightly': Yum repo downloading error: Downloading error(s): repodata/ad91db8cb7273beaefca0e473d9c4dd12d12786819947d9abc971661c588e8c6-primary.xml.gz - Cannot download, all mirrors were already tried without success; repodata/7062058d3e5395b4b02570496e41e19e8fd306f5234003a6c3595331cf3fc100-filelists.xml.gz - Cannot download, all mirrors were already tried without success

Change-Id: Id114d55edc2ba92f7851243ab7df51db332079c4
1 file changed