Rename traces methods/objects to include Traces in Kafka receiver

[sincejune]

Description:
Renamed methods/objects used by Traces to include "Traces" in Kafka receiver.
Fixed #2944 (comment)

[codecov]

Codecov Report

Merging #2966 (d432377) into main (0a2ea1b) will not change coverage.
The diff coverage is 100.00%.

@@           Coverage Diff           @@
##             main    #2966   +/-   ##
=======================================
  Coverage   91.63%   91.63%           
=======================================
  Files         312      312           
  Lines       15445    15445           
=======================================
  Hits        14153    14153           
  Misses        883      883           
  Partials      409      409           

Impacted Files	Coverage Δ
receiver/kafkareceiver/jaeger_unmarshaller.go	100.00% <ø> (ø)
receiver/kafkareceiver/otlp_unmarshaller.go	100.00% <ø> (ø)
receiver/kafkareceiver/zipkin_unmarshaller.go	92.59% <ø> (ø)
receiver/kafkareceiver/factory.go	100.00% <100.00%> (ø)
receiver/kafkareceiver/kafka_receiver.go	100.00% <100.00%> (ø)
receiver/kafkareceiver/unmarshaller.go	100.00% <100.00%> (ø)

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