tracing: correctly scope utxocache:flush tracepoint

Previously, the `utxocache:flush` tracepoint was in the wrong scope and
reached every time `CChainState::FlushStateToDisk` was called, even when
there was no flushing of the cache. The tracepoint is now properly scoped
and will be reached during a full flush.

Inside the scope, the `fDoFullFlush` value will always be `true`, so it
doesn't need to be logged separately. Hence, it's dropped from the
tracepoint arguments.

contrib/tracing/log_utxocache_flush.py

@@ -20,7 +20,6 @@ struct data_t
   u64 coins_count;
   u64 coins_mem_usage;
   bool is_flush_prune;
-  bool is_full_flush;
 };
 
 // BPF perf buffer to push the data to user space.
@@ -33,7 +32,6 @@ int trace_flush(struct pt_regs *ctx) {
   bpf_usdt_readarg(3, ctx, &data.coins_count);
   bpf_usdt_readarg(4, ctx, &data.coins_mem_usage);
   bpf_usdt_readarg(5, ctx, &data.is_flush_prune);
-  bpf_usdt_readarg(5, ctx, &data.is_full_flush);
   flush.perf_submit(ctx, &data, sizeof(data));
   return 0;
 }
@@ -55,18 +53,16 @@ class Data(ctypes.Structure):
         ("coins_count", ctypes.c_uint64),
         ("coins_mem_usage", ctypes.c_uint64),
         ("is_flush_prune", ctypes.c_bool),
-        ("is_full_flush", ctypes.c_bool)
     ]
 
 
 def print_event(event):
-    print("%-15d %-10s %-15d %-15s %-8s %-8s" % (
+    print("%-15d %-10s %-15d %-15s %-8s" % (
         event.duration,
         FLUSH_MODES[event.mode],
         event.coins_count,
         "%.2f kB" % (event.coins_mem_usage/1000),
         event.is_flush_prune,
-        event.is_full_flush
     ))
 
 
@@ -87,9 +83,9 @@ def main(bitcoind_path):
 
     b["flush"].open_perf_buffer(handle_flush)
     print("Logging utxocache flushes. Ctrl-C to end...")
-    print("%-15s %-10s %-15s %-15s %-8s %-8s" % ("Duration (µs)", "Mode",
-                                                 "Coins Count", "Memory Usage",
-                                                 "Prune", "Full Flush"))
+    print("%-15s %-10s %-15s %-15s %-8s" % ("Duration (µs)", "Mode",
+                                            "Coins Count", "Memory Usage",
+                                            "Prune"))
 
     while True:
         try: