Change default downstream packaging suffix to `+apertisX`

We moved from coX to apertisX as the packaging suffix but unfortunately it turned out to interact badly with the build suffix on OBS in some scenarios:

1. bluez in Debian has the 5.55-3 version
2. it gets uploaded to OBS with no changes, forgetting to add the apertisX suffix
3. OBS appends the build suffix, generating binaries with version 5.55-3bv2022dev2b1
4. we update bluez appending the apertisX suffix, yielding 5.55-3apertis1
5. OBS appends the build suffix, generating binaries with version 5.55-3apertis1bv2022dev2b1
6. reprepro gets the new binaries from OBS but the ordering is now wrong since 5.55-3apertis1bv2022dev2b1 < 5.55-3bv2022dev2b1 and will refuse to publish the newly built binaries

Switching to +apertisX has the following advantages:

• it can be rolled out progressively using the standard workflow
• no need to change the build suffix
  • no need to rebuild everything on OBS
  • no need to manually delete entries from reprepro
• backports work correctly, +apertisX sorts newer than coX and the OBS suffixes
• mixing releases like v2021 and v2022 should not produce surprising effects like v2021 builds sorting newer than v2022

The drawbacks are:

• every non-Apertis-specific package needs to be tweaked
• if Debian package maintainer releases a new version by appending a suffix there are higher chances that the +apertisX suffix will sort newer (we already have this issue, but this increases the chances to hit it)

Task: T7906