chore: Improve usage of test_name in the Acceptance test workflow

[maastha]

Description

This PR improves usage of test_name in the Acceptance test workflow .

Link to any related issue(s):

Type of change:

• [ ] Bug fix (non-breaking change which fixes an issue). Please, add the "bug" label to the PR.
• [ ] New feature (non-breaking change which adds functionality). Please, add the "enhancement" label to the PR. A migration guide must be created or updated if the new feature will go in a major version.
• [ ] Breaking change (fix or feature that would cause existing functionality to not work as expected). Please, add the "breaking change" label to the PR. A migration guide must be created or updated.
• [ ] This change requires a documentation update
• [ ] Documentation fix/enhancement

Required Checklist:

• [ ] I have signed the MongoDB CLA
• [ ] I have read the contributing guides
• [ ] I have checked that this change does not generate any credentials and that they are NOT accidentally logged anywhere.
• [ ] I have added tests that prove my fix is effective or that my feature works per HashiCorp requirements
• [ ] I have added any necessary documentation (if appropriate)
• [ ] I have run make fmt and formatted my code
• [ ] If changes include deprecations or removals, I defined an isolated PR with a relevant title as it will be used in the auto-generated changelog.
• [ ] If changes include removal or addition of 3rd party GitHub actions, I updated our internal document. Reach out to the APIx Integration slack channel to get access to the internal document.

Further comments

[lantoli]

knit: these two lines can be reverted:

mustTrigger: ${{ github.event_name == 'schedule' || (github.event_name == 'workflow_dispatch' && inputs.test_group == '' && inputs.test_name == '')  }}

if: ${{ inputs.test_group == '' && inputs.test_name == '' && env.mustTrigger == 'false' }}

to the previous version without test_name:

mustTrigger: ${{ github.event_name == 'schedule' || (github.event_name == 'workflow_dispatch' && inputs.test_group == '' )  }}

if: ${{ inputs.test_group == ''  && env.mustTrigger == 'false' }}

We're saying that when using test_name a test_group must be specified, so if we're not using a test_group ( inputs.test_group == '') then we're sure that test_name is empty, no need to check it

[EspenAlbert]

Nice!