When a CompositeMeterRegistry is used and one of its CompositeMeters
is polled (its value is fetched), the returned value can depend on
the order of the registries inside of the composite if the composite
contains a registry that has any NoopMeters.

Example: a CompositeMeterRegistry contains two registries, A and B.
We create a counter in the composite and increment it once.
After this both A and B contain one counter but lets say that
in A the counter is ignored so it will be noop.
When the count called on CompositeCounter, it can return
either 0 (if NoopCounter was used)
or 1 (if the non-noop counter was used).

In order to fix this, we can ignore the NoopMeters
when Meters are polled in a composite registry.

Closes micrometer-metricsgh-1441

…h-1441