xds: Remove xds authority label from metric registration (v1.69.x backport)

[DNVindhya]

XdsClient metrics were added in #11661. It is missing grpc.xds.authority label for grpc.xds_client.resources gauge.

While label value is absent, label got added while registering the gauge. This leads to java.lang.IllegalArgumentException: Incorrect number of required labels provided. on invoking callback. Stack trace is added below:

00:25:09.808 [PeriodicMetricReader-1] WARN  i.o.s.m.i.state.CallbackRegistration - An exception occurred invoking callback for CallbackRegistration{instrumentDescriptors=[InstrumentDescriptor{name=grpc.xds_client.resources, description=EXPERIMENTAL.  Number of xDS resources., unit={resource}, type=OBSERVABLE_GAUGE, valueType=LONG, advice=Advice{explicitBucketBoundaries=null, attributes=null}}, InstrumentDescriptor{name=grpc.xds_client.connected, description=EXPERIMENTAL. Whether or not the xDS client currently has a working ADS stream to the xDS server. For a given server, this will be set to 1 when the stream is initially created. It will be set to 0 when we have a connectivity failure or when the ADS stream fails without seeing a response message, as per gRFC A57. Once set to 0, it will be reset to 1 when we receive the first response on an ADS stream., unit={bool}, type=OBSERVABLE_GAUGE, valueType=LONG, advice=Advice{explicitBucketBoundaries=null, attributes=null}}]}.
java.lang.IllegalArgumentException: Incorrect number of required labels provided. Expected: 4
    at com.google.common.base.Preconditions.checkArgument(Preconditions.java:191)
    at io.grpc.MetricRecorder$BatchRecorder.recordLongGauge(MetricRecorder.java:138)
    at io.grpc.internal.MetricRecorderImpl$BatchRecorderImpl.recordLongGauge(MetricRecorderImpl.java:199)
    at io.grpc.xds.XdsClientMetricReporterImpl$MetricReporterCallback.reportResourceCountGauge(XdsClientMetricReporterImpl.java:205)
    at io.grpc.xds.XdsClientMetricReporterImpl.lambda$computeAndReportResourceCounts$1(XdsClientMetricReporterImpl.java:172)
    at java.base/java.util.HashMap.forEach(HashMap.java:1337)
    at io.grpc.xds.XdsClientMetricReporterImpl.computeAndReportResourceCounts(XdsClientMetricReporterImpl.java:171)
    at io.grpc.xds.XdsClientMetricReporterImpl.reportCallbackMetrics(XdsClientMetricReporterImpl.java:146)
    at io.grpc.xds.XdsClientMetricReporterImpl$1.accept(XdsClientMetricReporterImpl.java:123)
    at io.grpc.internal.MetricRecorderImpl.lambda$registerBatchCallback$0(MetricRecorderImpl.java:177)
    at io.opentelemetry.sdk.metrics.internal.state.CallbackRegistration.invokeCallback(CallbackRegistration.java:84)
    at io.opentelemetry.sdk.metrics.SdkMeter.collectAll(SdkMeter.java:112)
    at io.opentelemetry.sdk.metrics.SdkMeterProvider$LeasedMetricProducer.produce(SdkMeterProvider.java:208)
    at io.opentelemetry.sdk.metrics.SdkMeterProvider$SdkCollectionRegistration.collectAllMetrics(SdkMeterProvider.java:232)
    at io.opentelemetry.sdk.metrics.export.PeriodicMetricReader$Scheduled.doRun(PeriodicMetricReader.java:161)
    at io.opentelemetry.sdk.metrics.export.PeriodicMetricReader$Scheduled.run(PeriodicMetricReader.java:153)
    at java.base/java.util.concurrent.Executors$RunnableAdapter.call(Executors.java:515)
    at java.base/java.util.concurrent.FutureTask.runAndReset(FutureTask.java:305)
    at java.base/java.util.concurrent.ScheduledThreadPoolExecutor$ScheduledFutureTask.run(ScheduledThreadPoolExecutor.java:305)
    at java.base/java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1128)
    at java.base/java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:628)
    at java.base/java.lang.Thread.run(Thread.java:829)

As a fix, we are removing the label from gauge registration until gpc.xds.authority label value is available.

Backport of #11760