all: replace internal/telemetry by internal/newtelemetry

[eliottness]

What does this PR do?

This PR replace the old telemetry client with the new one. It does, in order:

• git rm -r internal/telemetry
• git mv internal/newtelemetry internal/telemetry
• Apply changes on the parts of the API that changed signicantly:
  • The way to start a new telemetry client is different, no more telemetry.ApplyOps
  • The API for metrics has been changed for better performances
• Rework the internal/telemetry/telemetrytest package because it was not using github.com/stretchr/testify/mock correctly (like, not at all)
• Update a literral TON of tests that were using the horrible telemetrytest API

Motivation

Better telemetry and support for telemetry metrics in the customer request hot path.
RFC: https://docs.google.com/document/d/1C3xoTZHQZNQ-Jr1w5mMThIkpHNW_4qKRf-J5CNi7G-k/edit?pli=1&tab=t.0#heading=h.88xvn2cvs9dt

Reviewer's Checklist

• Changed code has unit tests for its functionality at or near 100% coverage.
• System-Tests covering this feature have been added and enabled with the va.b.c-dev version tag.
• 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.
• Non-trivial go.mod changes, e.g. adding new modules, are reviewed by @DataDog/dd-trace-go-guild.
• For internal contributors, a matching PR should be created to the v2-dev branch and reviewed by @DataDog/apm-go.

APPSEC-56655

[datadog-datadog-prod-us1]

Datadog Report

Branch report: eliott.bouhana/remove-oldtelemetry
Commit report: f666b02
Test service: dd-trace-go

✅ 0 Failed, 5347 Passed, 72 Skipped, 3m 1.51s Total Time
⌛ 1 Performance Regression

⌛ Performance Regressions vs Default Branch (1)

• TestTracerCleanStop - gopkg.in/DataDog/dd-trace-go.v1/ddtrace/tracer 1m 48.03s (+1m 34.96s, +727%) - Details

[pr-commenter]

Benchmarks

Benchmark execution time: 2025-02-20 12:45:47

Comparing candidate commit 955e279 in PR branch eliott.bouhana/remove-oldtelemetry with baseline commit 3e85356 in branch main.

Found 0 performance improvements and 4 performance regressions! Performance is the same for 58 metrics, 0 unstable metrics.

scenario:BenchmarkOTelApiWithCustomTags/otel_api-24

• 🟥 allocated_mem [+115 bytes; +124 bytes] or [+2.385%; +2.567%]
• 🟥 allocations [+2; +2] or [+4.651%; +4.651%]
• 🟥 execution_time [+343.263ns; +393.537ns] or [+4.742%; +5.437%]

scenario:BenchmarkSetTagMetric-24

• 🟥 execution_time [+4.460ns; +7.100ns] or [+3.739%; +5.951%]

[nsrip-dd]

I'll confess I didn't read most of this too closely, but the profiling bits look reasonable. Thanks for tackling this!

[mtoffl01]

Do we need this log? Debug mode is typically used by customers when troubleshooting some issue, but customers don't even have access to telemetry, so not sure we need it?

[eliottness]

This would not even be in the diff if not for the sed command I ran that changed it :)
Hopefully I do another PR after this one that fixes mistakes and gaps in our telemetry usage. I can include the removal of this line in this future PR 👍

[RomainMuller]

LGTM for stuff under internal/appsec.