Remove getTransactionsUpdated() from mining interface

It's unnecessary to expose it via this interface.

src/node/interfaces.cpp

@@ -984,11 +984,6 @@ public:
         return chainman().ProcessNewBlock(block, /*force_processing=*/true, /*min_pow_checked=*/true, /*new_block=*/new_block);
     }
 
-    unsigned int getTransactionsUpdated() override
-    {
-        return context()->mempool->GetTransactionsUpdated();
-    }
-
     std::unique_ptr<BlockTemplate> createNewBlock(const BlockCreateOptions& options) override
     {
         BlockAssembler::Options assemble_options{options};