* tracing: Add new [tracing.opentelemetry] custom_attributes config setting Signed-off-by: Dave Henderson <dave.henderson@grafana.com> * Fix typos in config Signed-off-by: Dave Henderson <dave.henderson@grafana.com> * Return error when custom_attributes contains malformed entries Signed-off-by: Dave Henderson <dave.henderson@grafana.com> Signed-off-by: Dave Henderson <dave.henderson@grafana.com>