refactor(otel): use Apache HttpClient for cross-version compatibility

Address PR review feedback - use Apache HttpClient instead of platform httpPost API.

Changes:
- Replace IntelliJ Platform httpPost with Apache HttpClient
- Works consistently across all IDE versions (2024.2 - 2025.3+)
- Matches existing pattern used in SigV4OtlpSpanProcessor
- No version-specific compatibility wrappers needed
- Single OTelService.kt in common src/ directory

This approach:
- Uses same HTTP library as CawsEnvironmentClient and SigV4OtlpSpanProcessor
- Avoids platform API incompatibilities between IDE versions
- Follows established codebase patterns for HTTP operations

Author: aseemxs

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

@@ -25,6 +25,9 @@ import io.opentelemetry.sdk.trace.SpanProcessor
 import kotlinx.coroutines.CancellationException
 import kotlinx.coroutines.CoroutineScope
 import kotlinx.coroutines.launch
+import org.apache.http.client.methods.HttpPost
+import org.apache.http.entity.ByteArrayEntity
+import org.apache.http.impl.client.HttpClients
 import software.amazon.awssdk.auth.credentials.AwsCredentialsProvider
 import software.amazon.awssdk.http.ContentStreamProvider
 import software.amazon.awssdk.http.HttpExecuteRequest
@@ -48,7 +51,19 @@ private class BasicOtlpSpanProcessor(
         coroutineScope.launch {
             try {
                 val item = TraceRequestMarshaler.create(listOf(data))
-                sendOtelTrace(traceUrl, item)
+                val baos = ByteArrayOutputStream()
+                item.writeBinaryTo(baos)
+
+                HttpClients.createDefault().use { client ->
+                    val request = HttpPost(traceUrl).apply {
+                        entity = ByteArrayEntity(baos.toByteArray()).apply {
+                            setContentType("application/x-protobuf")
+                        }
+                    }
+                    client.execute(request).use {
+                        // Response consumed and closed
+                    }
+                }
             } catch (e: CancellationException) {
                 throw e
             } catch (e: ConnectException) {