app-layer/parser: remove misleading comment

Fixes: 833a738dd1 ("http: fail tx creation if we cannot allocate user data")

src/app-layer-parser.c

@@ -847,7 +847,6 @@ void AppLayerParserSetTransactionInspectId(const Flow *f, AppLayerParserState *p
             if (state_progress < state_done_progress)
                 break;
 
-            /* txd can be NULL for HTTP sessions where the user data alloc failed */
             AppLayerTxData *txd = AppLayerParserGetTxData(ipproto, alproto, tx);
             const uint8_t inspected_flag = (flags & STREAM_TOSERVER) ? APP_LAYER_TX_INSPECTED_TS
                                                                      : APP_LAYER_TX_INSPECTED_TC;