Move global metric back to otel/metric/global for minor release (#3986)

* Revert "Remove the deprecated `otel/metric/global` pkg (#3829)"

This reverts commit 60f7d42d1e.

* Revert "Support a global MeterProvider in `go.opentelemetry.io/otel` (#3818)"

This reverts commit 813936187e.

* Remove top level metric global

* Add change to changelog

internal/global/state.go

@@ -19,7 +19,6 @@ import (
 	"sync"
 	"sync/atomic"
 
-	"go.opentelemetry.io/otel/metric"
 	"go.opentelemetry.io/otel/propagation"
 	"go.opentelemetry.io/otel/trace"
 )
@@ -32,20 +31,14 @@ type (
 	propagatorsHolder struct {
 		tm propagation.TextMapPropagator
 	}
-
-	meterProviderHolder struct {
-		mp metric.MeterProvider
-	}
 )
 
 var (
-	globalTracer        = defaultTracerValue()
-	globalPropagators   = defaultPropagatorsValue()
-	globalMeterProvider = defaultMeterProvider()
+	globalTracer      = defaultTracerValue()
+	globalPropagators = defaultPropagatorsValue()
 
 	delegateTraceOnce             sync.Once
 	delegateTextMapPropagatorOnce sync.Once
-	delegateMeterOnce             sync.Once
 )
 
 // TracerProvider is the internal implementation for global.TracerProvider.
@@ -109,34 +102,6 @@ func SetTextMapPropagator(p propagation.TextMapPropagator) {
 	globalPropagators.Store(propagatorsHolder{tm: p})
 }
 
-// MeterProvider is the internal implementation for global.MeterProvider.
-func MeterProvider() metric.MeterProvider {
-	return globalMeterProvider.Load().(meterProviderHolder).mp
-}
-
-// SetMeterProvider is the internal implementation for global.SetMeterProvider.
-func SetMeterProvider(mp metric.MeterProvider) {
-	current := MeterProvider()
-	if _, cOk := current.(*meterProvider); cOk {
-		if _, mpOk := mp.(*meterProvider); mpOk && current == mp {
-			// Do not assign the default delegating MeterProvider to delegate
-			// to itself.
-			Error(
-				errors.New("no delegate configured in meter provider"),
-				"Setting meter provider to it's current value. No delegate will be configured",
-			)
-			return
-		}
-	}
-
-	delegateMeterOnce.Do(func() {
-		if def, ok := current.(*meterProvider); ok {
-			def.setDelegate(mp)
-		}
-	})
-	globalMeterProvider.Store(meterProviderHolder{mp: mp})
-}
-
 func defaultTracerValue() *atomic.Value {
 	v := &atomic.Value{}
 	v.Store(tracerProviderHolder{tp: &tracerProvider{}})
@@ -148,9 +113,3 @@ func defaultPropagatorsValue() *atomic.Value {
 	v.Store(propagatorsHolder{tm: newTextMapPropagator()})
 	return v
 }
-
-func defaultMeterProvider() *atomic.Value {
-	v := &atomic.Value{}
-	v.Store(meterProviderHolder{mp: &meterProvider{}})
-	return v
-}