Review and optimise test

[darius279]

As a user, I want to optimise the test execution

Description

Running the test using the gitHub action, we noticed that some test has too much gas consumption. For that reason, we should figure out a solution that allow us to reduce the total gas used.

Acceptance criteria

• All the test are executed successfully
• The overall gas is less than previously

### Tasks
- [ ] https://github.com/hashgraph/stablecoin-studio/issues/972