Test: criação do teste do metodo FormatInstant

[igorpenhaa]

Producing new tests #8557

Fixes #8557

Outline of Solution

increasing code coverage

fault identification: the LocalDateTime method is tested with the default of the developer's machine.

[github-actions]

Hi @igorpenhaa, thank you for your interest in contributing to TEAMMATES!
However, your PR does not appear to follow our contribution guidelines:

• Title must start with the issue number the PR is fixing in square brackets, e.g. [#<issue-number>]

Please address the above before we proceed to review your PR.

[weiquu]

Hi @igorpenhaa, ignoring the failing lint tests, I don't think this PR actually addresses the issue raised in #8557

The issue is that there are tests which fail if the system locale is set to a locale that uses different date/decimal formats. I set my system locale to Germany and ran ./gradlew componentTests which resulted in this failed test:

In contrast, all tests passed when I reset my system locale back to Singapore.

Your PR seems to be adding tests to the TimeHelper util, but I don't think it actually increases the code coverage. Do let me know if I have misunderstood.

[zhaojj2209]

Closing as PR does not address issue, see above.