Maintenance: migrate test runner to vitest for metrics package

[dreamorosi]

Summary

To continue the migration from Jest to Vitest we need to move over the tests for the metrics package to use the new test runner.

Why is this needed?

So that we can continue the migration as well as improve the overall performance and consistency of the tests.

Which area does this relate to?

Tests

Solution

No response

Acknowledgment

• This request meets Powertools for AWS Lambda (TypeScript) Tenets
• Should this be considered in other Powertools for AWS Lambda languages? i.e. Python, Java, and .NET

Future readers

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