refactor(experimental/examples/opencensus-shim): use new exported string constants for semconv#4763

pichlermarc merged 2 commits intoopen-telemetry:mainopen-telemetry/opentelemetry-js:mainfrom

Zen-cronic:experimental-examples-opencensus-shim-semconvZen-cronic/opentelemetry-js:experimental-examples-opencensus-shim-semconvCopy head branch name to clipboard