DEBUG-3535 DRY Transport::HTTP::Builder, move to core

[p-datadog]

What does this PR do?

Combines Tracing and Remote Config HTTP builders into one and moves it into core.

Motivation:

DI requires UDS transport which would have involved copying the existing transports, in particular adding a third copy of the Builder. Since the builders are almost identical I decided to DRY up the existing ones so that we would only need one.

Change log entry
None

Additional Notes:

How to test the change?
Existing unit tests

[github-actions]

Thank you for updating Change log entry section 👏

^{Visited at: 2025-02-19 22:18:07 UTC}

[pr-commenter]

Benchmarks

Benchmark execution time: 2025-02-19 22:43:41

Comparing candidate commit 4b5aa20 in PR branch di-uds with baseline commit 2df231f in branch master.

Found 0 performance improvements and 0 performance regressions! Performance is the same for 31 metrics, 2 unstable metrics.

[datadog-datadog-prod-us1]

Datadog Report

Branch report: di-uds
Commit report: 4b5aa20
Test service: dd-trace-rb

✅ 0 Failed, 20604 Passed, 1371 Skipped, 3m 19.22s Total Time