security/clamav-lts: Fix plist errror with non-default _CLAMAVUSER value

PR: 281436
Reported by: Yani Karydis
Fixes: d88a21e41bab security/clamav-lts: Update to 1.0.7
MFH: 2024Q3

(cherry picked from commit af9d47a8c45c385fca1d54920b80c7953c5bb0f9)