Remove some dev-dependecies and cargo features to speed up compilation (#535)

* Remove default features from metrics-exporter-prometheus

Signed-off-by: Ludvig Liljenberg <4257730+ludfjig@users.noreply.github.com>

* Reduce some dependencies from opentelemetry-otlp

Signed-off-by: Ludvig Liljenberg <4257730+ludfjig@users.noreply.github.com>

* Remove crossbeam dependency by replacing soft-depricated crossbeam::thread::scope with std::thread::scope

Signed-off-by: Ludvig Liljenberg <4257730+ludfjig@users.noreply.github.com>

* Remove some goblin features we don't need

Signed-off-by: Ludvig Liljenberg <4257730+ludfjig@users.noreply.github.com>

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Signed-off-by: Ludvig Liljenberg <4257730+ludfjig@users.noreply.github.com>

Author: ludfjig