repo-install-test: fix test_conflict for debian 13
Two changes are necessary to make this test work with debian 13:
* Installing libosmocore from osmocom-latest, then switching to osmocom-nightly and attempting to install another package is not enough anymore to trigger a conflict. apt is now able to resolve this by uninstalling the osmocom-latest package and upgrading libosmocore to the nightly version. Force the conflict by explicitly marking osmocom-latest (osmocom-$FEED) as installed and for hold.
* The apt conflict message has been reworked, so the string to look for needs to be adjusted.
The following packages have unmet dependencies: sdcc-dbgsym : Depends: sdcc (= 4.2.0~osmocom3.113.9edd) but 4.5.0+dfsg-1 is to be installed E: Unable to correct problems, you have held broken packages. E: The following information from --solver 3.0 may provide additional context: Unable to satisfy dependencies. Reached two conflicting decisions: 1. sdcc:amd64=4.2.0~osmocom3.113.9edd is not selected for install 2. sdcc:amd64=4.2.0~osmocom3.113.9edd is selected for install because: 1. sdcc-dbgsym:amd64=4.2.0~osmocom3.113.9edd is selected for install 2. sdcc-dbgsym:amd64 Depends sdcc (= 4.2.0~osmocom3.113.9edd)
This package from strongswan-epdg causes the SSH connection to QEMU to break when installed in debian 13. Don't install it. Use the wildcard, because there is also a debug symbols package that pulls in charon-systemd.
PyHSS listens on the same port as OsmoHLR, which causes the test to fail with debian 13 because OsmoHLR can't start up properly. PyHSS wasn't built for earlier debian versions in the Osmocom binary repositories.
