logging: fix the length limit of packages info dbg message

Should fix

23:22:51,735 WARNING rsyslogd:message too long (8104) with configured
size 8096, begin of message is: anaconda: main: Image packages:
fuse3-libs-3.16.2-4.fc41.x86_64 gawk-5.3.0-4.fc4 [v8.2408.0-2.fc42 try
https://www.rsyslog.com/e/2445 ]

anaconda.py

@@ -241,7 +241,7 @@ def setup_environment():
 
     log.info("%s %s", sys.argv[0], util.get_anaconda_version_string(build_time_version=True))
     # Do not exceed default 8K limit on message length in rsyslog
-    for log_line in util.get_image_packages_info(max_string_chars=8096-100):
+    for log_line in util.get_image_packages_info(max_string_chars=8096-120):
         log.debug("Image packages: %s", log_line)
 
     if opts.updates_url: