fix: Sampling Processor not removing higher level objs

[dpaasman00]

Proposed Change

While testing the Sampling Processor I noticed that in BindPlane the 'Filter Debug Logs' processor recommendation was being recommended despite no debug logs being present.

After debugging, I discovered this was occurring because this processor only deleted log records, leaving behind the parent scope and resource level objects. This was causing these objects to be initialized with default values when they were technically empty.

This change cleans up these objects if they are effectively empty. So resource spans/metrics/logs are removed if there are no scope entries, and scope spans/metrics/logs are removed if there are no spans/metrics/logRecords present. This successfully removes the filter debug recommendation.

To test, add the following replace statements to the transform agent go.mod, and then configure local bindplane to use this build of the transform agent (or just use a remote bta with this build).

replace github.com/observiq/bindplane-agent/processor/samplingprocessor => github.com/observiq/bindplane-agent/processor/samplingprocessor v1.60.1-0.20240925175304-a8f9052d43bf
replace github.com/observiq/bindplane-agent/expr => github.com/observiq/bindplane-agent/expr v1.60.1-0.20240925175304-a8f9052d43bf

Checklist

• Changes are tested
• CI has passed