fix(tracer, metrics): use polling instead of fixed wait in e2e tests

[ghost]

Description of your changes

This PR changes the way the E2E tests for metrics and tracer perform their checks.
Instead of waiting for a fixed amount of time (and hoping that the expected data will be available after the wait time elapses), the tests will now actively and periodically poll the corresponding services (CloudWatch metrics, X-Ray traces). When the expected number of result items arrives, the tests will perform their validation as usual. In case there will be not enough (or too many) items, the polling will stop after a timeout, so the tests will fail as intended.

The implementation relies on polling using unique IDs as keys. For metrics, the namespaces already represent such unique IDs in form of UUIDs. For traces, instead of introducing additional UUID annotations, it turned out to be easier to use unique Lambda function names for each test run.

This PR adds a new dev dependency: the promise-retry package (and its corresponding type declaration package).

How to verify this change

Run the E2E tests for tracer and metrics multiple times:

cd ./packages/tracing/ && for i in {1..10}; do npm run test:e2e; done && cd ..
cd ./packages/metrics/ && for i in {1..10}; do npm run test:e2e; done && cd ..

Explore the test results.

NOTE: The tests might fail for a different (legitimate) reason, so a red test result doesn't necessarily mean an issue with this PR. If any test fails, compare the actual stored trace or metric data with the expected values using AWS CLI or the Management Console. If the values differ, the test failure is caused not by the way the tests gather the data, so those failures must be investigated separately.

Related issues, RFCs

#644

PR status

Is this ready for review?: YES
Is it a breaking change?: NO

Checklist

• My changes meet the tenets criteria
• I have performed a self-review of my own code
• I have commented my code where necessary, particularly in areas that should be flagged with a TODO, or hard-to-understand areas
• I have made corresponding changes to the documentation
• I have made corresponding changes to the examples
• My changes generate no new warnings
• The code coverage hasn't decreased
• I have added tests that prove my change is effective and works
• New and existing unit tests pass locally and in Github Actions
• Any dependent changes have been merged and published in downstream module
• The PR title follows the conventional commit semantics

Breaking change checklist

• I have documented the migration process
• I have added, implemented necessary warnings (if it can live side by side)

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[flochaz]

Nice !

[dreamorosi]

Hi @AWSDB thanks a lot for the PR, just ran the e2e tests a couple of times and the duration of the tracer one went down more than 50%!

[dreamorosi]

Great one, thanks a lot.