[ct] update max child vasp in test
[ct] update max child vasp in test

The max supported child account is increased to 2^16 in ab391a0bd1. Update
the cluster test setup to be in sync.

Closes: #6974

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