[integration-test]Add configurable wait time for OTLP integration tests

[litianningdatadog]

https://datadoghq.atlassian.net/browse/SVLS-8286

Overview

We noticed OTLP integration tests were flaky. One speculation was we didn't wait long enough before retrieving the result.

Hence we made Datadog indexing wait time configurable and use 5-minute wait for OTLP tests (instead of default 60s) to accommodate longer data propagation delays through OTLP collector pipeline.

Testing

Local test:

npm test -- otlp.test.ts
...
   Waiting 300s for logs and traces to be indexed in Datadog...
...
Test Suites: 1 passed, 1 total
Tests:       13 passed, 13 total
Snapshots:   0 total
Time:        318.945 s