input_log: count input metrics once for conditional route fan-out

split_and_append_route_payloads() appended one chunk copy per matching
route through the metric-bearing append helpers, double counting the
input records and bytes that are already accounted for by the
unconditional append in input_log_append_processed_internal().

Use the new flags-aware append helpers with
FLB_INPUT_CHUNK_SKIP_INPUT_METRICS for the per-route copies so the
input-level totals reflect the original ingestion exactly once,
regardless of how many routes match.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
Signed-off-by: zshuang0316 <zshuang0316@163.com>

Author: zshuang0316

src/flb_input_log.c

@@ -1397,18 +1397,27 @@ static int split_and_append_route_payloads(struct flb_input_instance *ins,
             continue;
         }
 
+        /*
+         * These appends are internal route copies of data that is also
+         * ingested by the unconditional append in
+         * input_log_append_processed_internal(). Suppress the input-level
+         * metrics here so fluentbit_input_records_total / _bytes_total are
+         * counted once for the original ingestion instead of once per route.
+         */
         if (local_append == FLB_TRUE) {
-            ret = flb_input_chunk_append_raw_local(ins,
+            ret = flb_input_chunk_append_raw_local_flags(ins,
                                                    FLB_INPUT_LOGS,
+                                                   FLB_INPUT_CHUNK_SKIP_INPUT_METRICS,
                                                    payload->total_records,
                                                    payload->tag,
                                                    flb_sds_len(payload->tag),
                                                    payload->data,
                                                    payload->size);
         }
         else {
-            ret = flb_input_chunk_append_raw(ins,
+            ret = flb_input_chunk_append_raw_flags(ins,
                                              FLB_INPUT_LOGS,
+                                             FLB_INPUT_CHUNK_SKIP_INPUT_METRICS,
                                              payload->total_records,
                                              payload->tag,
                                              flb_sds_len(payload->tag),