tracing: fix panic on startup when configured
tracing: fix panic on startup when configured

When support for http/protobuf was added, the OTLP tracing processor
plugin was mistakenly changed to return a raw OTLP exporter instance.
Consequently, the type-assertion to a trace.SpanProcessor inside the
tracing pluigin would panic if the processor plugin was configured.
Modify the OTLP plugin to return a BatchSpanProcessor derived from the
exporter once more.

Signed-off-by: Cory Snider <2b734a4312be4b38906a3c89d31b95fd61f34b17@mirantis.com>

thaJeztah/containerd,thaJeztah/containerd,mikebrow/containerd,estesp/containerd,containerd/containerd,mikebrow/containerd,estesp/containerd,containerd/containerd