Check for instantiation of generic for type inference.

[MadVikingGod]

Check for instantiation of generic for type inference.

[dmathieu]

From a quick grep, I'm finding only one non-test occurence.

open-telemetry/opentelemetry-go›  git:(main) grep -rn 'var .* T' .
./trace/config.go:38:   var config TracerConfig
./trace/tracestate.go:175:var _ json.Marshaler = TraceState{}
./trace/noop.go:26:var _ TracerProvider = noopTracerProvider{}
./trace/noop.go:36:var _ Tracer = noopTracer{}
./trace/tracestate_test.go:279:var maxMembers = func() TraceState {
./trace/tracestate_test.go:412:var insertTS = TraceState{list: []member{
./exporters/zipkin/internal/internaltest/errors.go:11:var _ error = TestError("")
./internal/internaltest/errors.go:11:var _ error = TestError("")
./internal/shared/internaltest/errors.go.tmpl:11:var _ error = TestError("")
./sdk/trace/evictedqueue.go:23: var tVal T
./sdk/internal/internaltest/errors.go:11:var _ error = TestError("")
./sdk/internal/x/x_test.go:50:  var zero T
./sdk/metric/internal/x/x_test.go:60:   var zero T
./sdk/metric/view.go:112:       var zero T
./propagation/propagation.go:37:var _ TextMapCarrier = MapCarrier{}
./propagation/baggage.go:20:var _ TextMapPropagator = Baggage{}

opentelemetry-go/sdk/metric/view.go

Lines 110 to 117 in 499785e

	// nonZero returns v if it is non-zero-valued, otherwise alt.
	func nonZero[T comparable](v, alt T) T {
	var zero T
	if v != zero {
	return v
	}
	return alt
	}

We could remove the generics in this method, by passing a third argument into the method which would be the zero value.
Creating views shouldn't be in the hot path though, as it happens once at boot time.