[SEMCONV] Metrics are incorrectly prefixed with `metric.`

[sjinks]

Describe your environment OpenTelemetry 1.18

Steps to reproduce
When using CreateXXXMetricYY() functions from opentelemetry/api/semconv (for example, CreateAsyncInt64MetricProcessContextSwitches() or any other similar function), they create a metric prefixed with metric. (for example, metric.process.context_switches).

I believe this is not correct: for example, for the Context Switches metric, the specification says that the name is process.context_switches, not metric.process.context_switches.

What is the expected behavior?
Metric names match the specification.

What is the actual behavior?
Metric names have an additional prefix of metric..

Additional context
I think this bug was introduced in #3105, here:

static constexpr const char *{{v_metric_name}} = "{{metric.id}}";

By looking at the Process Metrics Model, we see:

  - id: metric.process.context_switches
    type: metric
    metric_name: process.context_switches
    stability: experimental
    brief: "Number of times the process has been context switched."
    instrument: counter
    unit: "{count}"
    attributes:
      - ref: process.context_switch_type

id is what we have now, metric_name is what we should probably have.

The fix I think will be (buildscripts/semantic-convention/templates/registry/semantic_metrics-h.j2)

-static constexpr const char *{{v_metric_name}} = "{{metric.id}}";
+static constexpr const char *{{v_metric_name}} = "{{metric.metric_name}}";