@envelop/opentelemetry: Change span names to reduce cardinality

**Is your feature request related to a problem? Please describe.**

The current implementation sets span names to `{parentType.name}.${fieldName}` which often leads to high cardinality.

**Describe the solution you'd like**

It would be great if @envelop/opentelemetry adopted [Semantic conventions for GraphQL server spans](https://opentelemetry.io/docs/specs/semconv/graphql/graphql-spans/)

**Describe alternatives you've considered**

**Additional context**

Start in the @envelop/opentelemetry implementation where span names are formed as {parentType.name}.{fieldName}. Read the linked Semantic conventions for GraphQL server spans and compare them with the current behavior. Done means the package follows the convention and reduces high-cardinality span names.

Written by the indexing model from the issue text.