Update runtime-telemetry-java17 to use stable semconv where applicable

[trask]

Looks like it's still using the old semconv, e.g.

opentelemetry-java-instrumentation/instrumentation/runtime-telemetry/runtime-telemetry-java17/library/src/main/java/io/opentelemetry/instrumentation/runtimemetrics/java17/internal/classes/ClassesLoadedHandler.java

Line 27 in cfd40a8

private static final String METRIC_NAME_LOADED = "process.runtime.jvm.classes.loaded";

[robsunday]

I can take this on, please assign to me