sysutils/bacula15-server: patch to fix upgrade script

With upcoming removal of bacula9 and bacula11, let's make this work.

These patches have been submitted upstream but not released:

• https://github.com/dlangille/bacula-community/commit/0200b1461310b4f5d4cdb89aedaa2ca9c1e1ad77
• https://github.com/dlangille/bacula-community/commit/716952b15b71be44f152bfb522666514422acc95

While here, remove Makefile.old committed during 9df94c4d9d1c50f758e9be67e51060a14527e2cc

PR: 281542