Update db instrumentations documentation around OTEL_SEMCONV_STABILITY_OPT_IN

Release [1.44.0/0.65b0](https://github.com/open-telemetry/opentelemetry-python-contrib/releases/tag/v0.65b0) supports `OTEL_SEMCONV_STABILITY_OPT_IN` for most database instrumentation libraries. Similar to https://github.com/open-telemetry/opentelemetry-python-contrib/issues/4202: * database - emit the new, stable db conventions, and stop emitting the old experimental db conventions that the instrumentation emitted previously. * database/dup - emit both the old and the stable db conventions, allowing for a seamless transition. By default, the old experimental db conventions are emitted. Please update the individual instrumentation libraries' documentation around this feature.