refactor: Remove stray cs_main redundant declaration

src/node/utxo_snapshot.cpp

@@ -7,12 +7,17 @@
 #include <fs.h>
 #include <logging.h>
 #include <streams.h>
+#include <sync.h>
+#include <tinyformat.h>
+#include <txdb.h>
 #include <uint256.h>
 #include <util/system.h>
 #include <validation.h>
 
+#include <cassert>
 #include <cstdio>
 #include <optional>
+#include <string>
 
 namespace node {
 

src/node/utxo_snapshot.h

@@ -7,13 +7,16 @@
 #define BITCOIN_NODE_UTXO_SNAPSHOT_H
 
 #include <fs.h>
-#include <uint256.h>
+#include <kernel/cs_main.h>
 #include <serialize.h>
-#include <validation.h>
+#include <sync.h>
+#include <uint256.h>
 
+#include <cstdint>
 #include <optional>
+#include <string_view>
 
-extern RecursiveMutex cs_main;
+class Chainstate;
 
 namespace node {
 //! Metadata describing a serialized version of a UTXO set from which an