log-pcap: remove early output initializing if offline

Remove early opening of output files if running in an offline mode, as
we don't yet know the timestamp to use.

Prevents the first pcap files being opened with a timestamp of 0,
bringing us back to the same behvaviour of pcap logging in 6.0.

Issue: 5374

src/log-pcap.c

@@ -1104,11 +1104,14 @@ static TmEcode PcapLogDataInit(ThreadVars *t, const void *initdata, void **data)
 #endif /* INIT_RING_BUFFER */
     }
 
-    if (pl->mode == LOGMODE_MULTI) {
-        PcapLogOpenFileCtx(td->pcap_log);
-    } else {
-        if (pl->filename == NULL) {
-            PcapLogOpenFileCtx(pl);
+    /* Don't early initialize output files if in a PCAP file mode. */
+    if (IsRunModeOffline(RunmodeGetCurrent())) {
+        if (pl->mode == LOGMODE_MULTI) {
+            PcapLogOpenFileCtx(td->pcap_log);
+        } else {
+            if (pl->filename == NULL) {
+                PcapLogOpenFileCtx(pl);
+            }
         }
     }