feat: update libdatadog revision to 0a3304c6aaf84738786b670d706a01edc22dab81

[duncanpharvey]

What does this PR do?

Updates libdatadog revision to DataDog/libdatadog@0a3304c.

Motivation

https://datadoghq.atlassian.net/browse/SVLS-9006

Additional Notes

• Follows feat(trace-utils)!: search all spans to populate tracer payload fields libdatadog#1954: feat(trace-utils)!: search all spans to populate tracer payload fields.
• Updates some dependencies with breaking changes

Describe how to test/QA your changes

Invoked .NET functions that undercounted some stats by version and validated that all trace stats submitted to intake have a version.

plow "$url" -c 50 -n 50000

With 50% sampling enabled: DD_TRACE_SAMPLING_RULES: [{"sample_rate":0.5}]

[Copilot]

Pull request overview

Updates this repo’s libdatadog git dependencies to revision 0a3304c6aaf84738786b670d706a01edc22dab81, aligning the trace agent code with upstream libdatadog API changes (notably around capabilities used for sending traces/stats).

Changes:

• Bumps libdd-* git dependency revisions across affected crates and updates Cargo.lock accordingly.
• Migrates the trace flusher HTTP client impl from HttpClientTrait to HttpClientCapability, and adds a SleepCapability impl required by the updated send/retry logic.
• Switches stats flushing to use NativeHttpClient (from libdd_capabilities_impl) when submitting stats payloads.

Reviewed changes

Copilot reviewed 6 out of 7 changed files in this pull request and generated no comments.

Show a summary per file

File	Description
crates/datadog-trace-agent/src/trace_flusher.rs	Updates proxy HTTP client to new libdd_capabilities traits and adds SleepCapability implementation.
crates/datadog-trace-agent/src/stats_flusher.rs	Uses NativeHttpClient for stats_utils::send_stats_payload after lib upgrade.
crates/datadog-trace-agent/Cargo.toml	Bumps all libdd-* git revs to the new libdatadog commit.
crates/datadog-serverless-compat/Cargo.toml	Bumps libdd-trace-utils git rev to match new libdatadog commit.
crates/datadog-metrics-collector/Cargo.toml	Bumps libdd-common git rev to match new libdatadog commit.
crates/datadog-agent-config/Cargo.toml	Bumps libdd-trace-obfuscation and libdd-trace-utils git revs to match new libdatadog commit.
Cargo.lock	Locks new libdatadog sources and updated transitive deps introduced by the bump.