tree-wide: set SD_JOURNAL_ASSUME_IMMUTABLE where appropriate

Co-authored-by: Costa Tsaousis <costa@netdata.cloud>

src/network/networkctl.c

@@ -1597,7 +1597,7 @@ static int show_logs(const LinkInfo *info) {
         if (arg_lines == 0)
                 return 0;
 
-        r = sd_journal_open(&j, SD_JOURNAL_LOCAL_ONLY);
+        r = sd_journal_open(&j, SD_JOURNAL_LOCAL_ONLY | SD_JOURNAL_ASSUME_IMMUTABLE);
         if (r < 0)
                 return log_error_errno(r, "Failed to open journal: %m");