Update OTel SDK to version 1.35 (#425)

## Goal

Update OTel to the latest version. Fixed `EmbraceSpanProcessor` to ensure the `onStart` method is always run

## Testing

Manually tested on an app that has the minimum requirements, and existing tests pass

buildSrc/src/main/kotlin/io/embrace/gradle/Versions.kt

@@ -39,7 +39,7 @@ object Versions {
  val ndk = "21.4.7075529"
 
  @JvmField
- val openTelemetry = "1.29.0"
+ val openTelemetry = "1.35.0"
 
  @JvmField
  val moshi = "1.12.0"

embrace-android-sdk/src/main/java/io/embrace/android/embracesdk/internal/spans/EmbraceSpanProcessor.kt

@@ -11,25 +11,21 @@ import java.util.concurrent.atomic.AtomicLong
 
 /**
  * [SpanProcessor] that adds custom attributes to a [Span] when it starts, and exports it to the given [SpanExporter] when it finishes
- *
- * Note: no explicit tests exist for this as its functionality is tested via the tests for [SpansServiceImpl]
  */
 @InternalApi
 internal class EmbraceSpanProcessor(private val spanExporter: SpanExporter) : SpanProcessor {
 
- // TODO: sequence-id should be persisted across cold starts to better gauge data loss
  private val counter = AtomicLong(1)
 
  override fun onStart(parentContext: Context, span: ReadWriteSpan) {
  span.setSequenceId(counter.getAndIncrement())
  }
 
  override fun onEnd(span: ReadableSpan) {
- // TODO: consider exporting this to a buffer that will export the collected Spans in bulk for performance reasons
  spanExporter.export(mutableListOf(span.toSpanData()))
  }
 
- override fun isStartRequired() = false
+ override fun isStartRequired() = true
 
  override fun isEndRequired() = true
 }