ddtrace/tracer: Switch default context propagation order

[JianyiGao]

What does this PR do?

This PR switch default context propagation order from tracecontext,datadog to datadog,tracecontext
The same change is merged into v2-dev branch, this PR is to cherry pick the same commit to main so system test can run with the new default context propagation order.
System test change: DataDog/system-tests#1853

Motivation

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.
• Add an appropriate team label so this PR gets put in the right place for the release notes.

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: 2024-02-05 22:03:25

Comparing candidate commit d8d48d4 in PR branch jennie.gao/cherrypick-3b07dd2 with baseline commit 42593ee in branch main.

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

[darccio]

@JianyiGao Just curious: why is this change going to be merged into main? It's a breaking change.

[JianyiGao]

@dianashevchenko suggested to add this change to main, we can also test the new default behavior on system tests. I am not aware that this is a breaking change, would you like to chime in Diana?

[felixge]

@JianyiGao Just curious: why is this change going to be merged into main? It's a breaking change.

AFAIK this is not a breaking change. See PROF-8549 for my notes on this or let's discuss in slack.

[github-actions]

This PR is stale because it has been open 20 days with no activity. Remove stale label or comment or this will be closed in 10 days.

[github-actions]

This PR is stale because it has been open 20 days with no activity. Remove stale label or comment or this will be closed in 10 days.

[mabdinur]

Parametric tests pass with the following commit: 288c76d

[mabdinur]

@katiehockman when you get a chance can you merge this PR 🥳