Enable otel runtime metrics & Don't emit Current Thread Count and Loaded Class Count to OTLP

[harsimar]

Multiple changes:

• Enable "otel.instrumentation.runtime-telemetry" metrics (see here)
• We currently have a couple metrics (Current Thread Count & Loaded Class Count) flowing to OTLP & Breeze. Since these two metrics also have analogous metrics in the otel runtime instrumentation, removed these two metrics from the OTLP code path (it just goes to Breeze to maintain backwards compatibility until v4).
• Some test changes to account for the new metrics enabled via the otel runtime instrumentation.