[cleaner] Improve IPV6 MAC address RE

Current RE obfuscates also UUID strings, let be more strict.

Resolves: #3766
Relevant: #3736

Signed-off-by: Pavel Moravec <pmoravec@redhat.com>

sos/cleaner/parsers/mac_parser.py

@@ -20,9 +20,12 @@
     r'[0-9a-fA-F]{2}(\'|\")?(\/|\,|\-|\.|\s|$))'
 )
 # aabb:ccee:ddee:ffaa
-IPV6_REG_4HEX = (
-    r'((?<!([0-9a-fA-F\'\"]:)|::)(([^:\-]?[0-9a-fA-F]{4}(:|-)){3}'
-    r'[0-9a-fA-F]{4}(\'|\")?(\/|\,|\-|\.|\s|$)))'
+# - but disallow "substrings"
+#   - but allow fe80: or fe80:: prefix for link-local
+IPV6_REG_4HEX_NEW = (
+        r'((?<!(?:([.|^|\b]{5}\w|[.|^|\b]fe80:|fe80::)))'
+        r'(([0-9a-fA-F]{4}:){3}[0-9a-fA-F]{4})(?!\w))|'
+        r'((?<!\w)(([0-9a-fA-F]{4}-){3}[0-9a-fA-F]{4})(?!\w))'
 )
 # aa:bb:cc:dd:ee:ff avoiding ipv6 substring matches
 IPV4_REG = (