chore: remove unused trace_exporter crate

The pipeline crate's WasmSpanState builds its own internal TraceExporter and
owns serialization + send (sendPreparedChunk), superseding the standalone
trace_exporter binding (JsTraceExporter, the earlier pre-encoded-v0.4-bytes
path). Nothing consumes it: dd-trace-js (native-spans and master) loads only
the pipeline crate, and no other tracked code references it. Drop the crate,
its wasm test, and the build/test wiring.

Author: bengl

Cargo.lock

@@ -9,7 +9,7 @@
     "build-debug": "mkdir -p target && yarn -s cargo-build > ./target/out.ndjson && yarn -s copy-artifacts",
     "build-release": "mkdir -p target && yarn -s cargo-build-release > ./target/out.ndjson && yarn -s copy-artifacts",
     "build-all": "mkdir -p target && yarn -s cargo-build -- --workspace > ./target/out.ndjson && yarn -s copy-artifacts && yarn -s build-wasm",
-    "build-wasm": "node scripts/build-wasm.js library_config && node scripts/build-wasm.js datadog-js-zstd && node scripts/build-wasm.js trace_exporter && node scripts/build-wasm.js pipeline",
+    "build-wasm": "node scripts/build-wasm.js library_config && node scripts/build-wasm.js datadog-js-zstd && node scripts/build-wasm.js pipeline",
     "cargo-build-release": "yarn -s cargo-build -- --release",
     "cargo-build": "cargo build --message-format=json-render-diagnostics",
     "copy-artifacts": "node ./scripts/copy-artifacts",

crates/trace_exporter/Cargo.toml

@@ -35,7 +35,3 @@ for d in test/*/; do
       ;;
   esac
 done
-
-# The wasm trace exporter integration test runs against its own in-process mock
-# agent, so run it directly (other test/wasm/* modules remain manual for now).
-run_test test/wasm/trace_exporter/index.js