Update-tool fails to update distributions that don't have the build.metadata file

Changes introduced in RHPAM-3917 changed the way to check if the version of the distribution could be upgraded. It started to check for the build.metadata file (as MANIFEST.MF changed the structure for 7.12.0 due to migration to EAP bootable jar) instead of MANIFEST.MF.

The problem is that the build.metadata is not available for all distributions (e.g kie-server.war), said that we need to use the MANIFEST.MF for the cases that the build.metadata is not available.