Async instruments don't do spatial reaggregation when attributes are dropped

[jack-berg]

As discussed in open-telemetry/opentelemetry-specification#2905, several languages don't do spatial reaggregation when attributes are dropped via views. Java is one of those languages.

Here's an example snippet that demonstrates the issue:

    InMemoryMetricReader reader = InMemoryMetricReader.create();
    SdkMeterProvider meterProvider =
        SdkMeterProvider.builder()
            .registerMetricReader(reader)
            .registerView(
                InstrumentSelector.builder().setName("my-instrument").build(),
                View.builder().setAttributeFilter(attributeKey -> false).build())
            .build();

    Meter myMeter = meterProvider.get("my-meter");

    LongUpDownCounterBuilder myInstrument = myMeter.upDownCounterBuilder("my-instrument");
    myInstrument.buildWithCallback(
        observable -> {
          observable.record(10, Attributes.builder().put("key", "value1").build());
          observable.record(10, Attributes.builder().put("key", "value2").build());
        });

    OpenTelemetryAssertions.assertThat(reader.collectAllMetrics())
        .satisfiesExactly(
            metricData ->
                OpenTelemetryAssertions.assertThat(metricData)
                    .hasLongSumSatisfying(
                        sum ->
                            sum.hasPointsSatisfying(
                                point ->
                                    point
                                        # .hasValue(20) // Correct behavior: should aggregate the two 10 values together
                                        .hasValue(10) // Actual behavior: takes the last reported measurement without aggregation
                                        .hasAttributes(
                                            Attributes.empty()))));