.github/workflows: improve nightly v2 CI workflows

[darccio]

What does this PR do?

Builds upon #2348 & #2359 to ensure nightly CI is run on v2-dev. Fixes for smoke and system tests on v2 will be done in a separate PR.

Motivation

We need to catch any possible issue early, as we aim to dogfood dd-trace-go/v2 in around a month.

Reviewer's Checklist

• Changed code has unit tests for its functionality at or near 100% coverage.
• There is a benchmark for any new code, or changes to existing code.
• If this interacts with the agent in a new way, a system test has been added.

For Datadog employees:

• If this PR touches code that handles credentials of any kind, such as Datadog API keys, I've requested a review from @DataDog/security-design-and-guidance.
• This PR doesn't touch any of that.

Unsure? Have a question? Request a review!

[pr-commenter]

Benchmarks

Benchmark execution time: 2023-11-15 16:15:57

Comparing candidate commit 8da343f in PR branch dario.castane/AIT-8917/final-v2-nightly-version with baseline commit 101c4d5 in branch main.

Found 0 performance improvements and 0 performance regressions! Performance is the same for 39 metrics, 2 unstable metrics.