[language/vm-runtime] remove unused MoveVM::execute_runtime
[language/vm-runtime] remove unused MoveVM::execute_runtime

Closes: #2729
Approved by: dariorussi

aptos-labs/aptos-core,libra/libra,aptos-labs/aptos-core,aptos-labs/aptos-core,libra/libra,aptos-labs/aptos-core,libra/libra,aptos-labs/aptos-core,libra/libra,aptos-labs/aptos-core,libra/libra,aptos-labs/aptos-core