update ci machine size to prevent timeouts/ooms in unit tests
update ci machine size to prevent timeouts/ooms in unit tests

Closes: #4804
Approved by: sausagee

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