This commit renames the tracing to telemetry.tracing in both xpack/APM and elasticserach's org.elasticsearch.tracing.Tracer (the api)
the xpack/APM is renamed as follows:
org.elasticsearch.telemetry.apm - the only exported package
org.elasticsearch.telemetry.apm.settings - APMSettings
org.elasticsearch.telemetry.apm.tracing - APMTracer
org.elasticsearch.tracing.Tracer is moved to org.elasticsearch.telemetry.tracing.Tracer (responsible for majority of the changes in this PR)
b6747b48ba