refactor(otel): use compatibility helpers instead of duplicating entire file

Address PR review feedback to avoid copying entire OTelService.kt for version compatibility.

Changes:
- Move OTelService.kt to common src/ directory (168 lines, shared by all versions)
- Create small version-specific HttpPostCompat.kt files (18-19 lines each)
- Eliminates 137 lines of code duplication
- Main logic now maintained in single location

The httpPost API changed between IDE versions 2024.2-2025.2 and 2025.3+:
- Old API uses contentLength parameter with streaming body
- New API uses body parameter with byte array

Follows existing codebase pattern (see PythonModuleUtil.kt, JavascriptLanguage.kt)
for handling compile-time API incompatibilities with minimal duplication.

Author: aseemxs

plugins/core/jetbrains-community/src-242-252/software/aws/toolkits/jetbrains/services/telemetry/otel/HttpPostCompat.kt

@@ -0,0 +1,18 @@
+// Copyright 2024 Amazon.com, Inc. or its affiliates. All Rights Reserved.
+// SPDX-License-Identifier: Apache-2.0
+
+package software.aws.toolkits.jetbrains.services.telemetry.otel
+
+import com.intellij.platform.util.http.ContentType
+import com.intellij.platform.util.http.httpPost
+import io.opentelemetry.exporter.internal.otlp.traces.TraceRequestMarshaler
+
+/**
+ * Version-specific compatibility wrapper for httpPost (2024.2-2025.2)
+ * In these versions, httpPost uses contentLength parameter with streaming body
+ */
+internal suspend fun sendOtelTrace(url: String, marshaler: TraceRequestMarshaler) {
+    httpPost(url, contentLength = marshaler.binarySerializedSize.toLong(), contentType = ContentType.XProtobuf) {
+        marshaler.writeBinaryTo(this)
+    }
+}

plugins/core/jetbrains-community/src-253+/software/aws/toolkits/jetbrains/services/telemetry/otel/HttpPostCompat.kt

@@ -0,0 +1,19 @@
+// Copyright 2024 Amazon.com, Inc. or its affiliates. All Rights Reserved.
+// SPDX-License-Identifier: Apache-2.0
+
+package software.aws.toolkits.jetbrains.services.telemetry.otel
+
+import com.intellij.platform.util.http.ContentType
+import com.intellij.platform.util.http.httpPost
+import io.opentelemetry.exporter.internal.otlp.traces.TraceRequestMarshaler
+import java.io.ByteArrayOutputStream
+
+/**
+ * Version-specific compatibility wrapper for httpPost (2025.3+)
+ * In this version, httpPost uses body parameter with byte array
+ */
+internal suspend fun sendOtelTrace(url: String, marshaler: TraceRequestMarshaler) {
+    val output = ByteArrayOutputStream()
+    marshaler.writeBinaryTo(output)
+    httpPost(url, contentType = ContentType.XProtobuf, body = output.toByteArray())
+}

plugins/core/jetbrains-community/src-253+/software/aws/toolkits/jetbrains/services/telemetry/otel/OTelService.kt

@@ -50,10 +50,7 @@ private class BasicOtlpSpanProcessor(
         coroutineScope.launch {
             try {
                 val item = TraceRequestMarshaler.create(listOf(data))
-
-                httpPost(traceUrl, contentLength = item.binarySerializedSize.toLong(), contentType = ContentType.XProtobuf) {
-                    item.writeBinaryTo(this)
-                }
+                sendOtelTrace(traceUrl, item)
             } catch (e: CancellationException) {
                 throw e
             } catch (e: ConnectException) {