Maintenance: make e2e test stack name unique

[flochaz]

Description of the feature request

Problem statement
As of today Stack names in e2e tests are static (see https://github.com/awslabs/aws-lambda-powertools-typescript/blob/main/packages/metrics/tests/e2e/decorator.test.ts#L23 for instance) which prevent us from running multiple instances of e2e against different branches.

Summary of the feature
Add a random unique id, a branch name or a commit id to stack name in all e2e.

Code examples

const stack = new Stack(integTestApp, `MetricsE2EDecoratorStack-${process.env.GITHUB_REF_NAME ? process.env.GITHUB_REF_NAME : 'unknown'}`);

List of available env var in github action: https://docs.github.com/en/actions/learn-github-actions/environment-variables

Benefits for you and the wider AWS community
Validate PR quickly

[ijemmy]

@flochaz I'm going to refactor metrics & tracer e2e tests to be like logger (using uuid). I can take over this if you're ok.