`lib/protoparser/prometheus` is used by various applications,
such as `app/vmalert`. The recent change to the
`lib/protoparser/prometheus` package introduced a new dependency
of `lib/writeconcurrencylimiter` which exposes some metrics.
Because of the dependency, now all applications which have this
dependency also expose these metrics.
Creating a new `lib/protoparser/prometheus/stream` package helps
to remove these metrics from apps which use `lib/protoparser/prometheus`
as dependency.
See https://github.com/VictoriaMetrics/VictoriaMetrics/issues/3761
Signed-off-by: hagen1778 <roman@victoriametrics.com>
