OpenAI instrumentation: embedding instrumentation metrics conformance

[lmolkova]

It seems openai instrumentation emits legacy metrics when in experimental mode

opentelemetry.test.weaver_live_check.LiveCheckError: Semconv violations found:
  - [deprecated] Attribute 'gen_ai.system' is deprecated; reason = 'renamed', note = 'Replaced by `gen_ai.provider.name`.'. (1 occurrence(s) on metric 'gen_ai.client.operation.duration')
  - [deprecated] Attribute 'gen_ai.system' is deprecated; reason = 'renamed', note = 'Replaced by `gen_ai.provider.name`.'. (1 occurrence(s) on metric 'gen_ai.client.token.usage')
  - [required_attribute_not_present] Required attribute 'gen_ai.provider.name' is not present. (1 occurrence(s) on metric 'gen_ai.client.operation.duration')
  - [required_attribute_not_present] Required attribute 'gen_ai.provider.name' is not present. (1 occurrence(s) on metric 'gen_ai.client.token.usage')

To reproduce: unskip corresponding scenario in conformance testing: #14