Rename leftover references to SpanData

[MrAlias]

Part of clean identified needed in #1380

[codecov]

Codecov Report

Merging #1736 (09a13a6) into main (382c7ce) will increase coverage by 0.0%.
The diff coverage is 100.0%.

@@          Coverage Diff          @@
##            main   #1736   +/-   ##
=====================================
  Coverage   77.9%   78.0%           
=====================================
  Files        131     131           
  Lines       6953    6953           
=====================================
+ Hits        5422    5424    +2     
+ Misses      1281    1279    -2     
  Partials     250     250           

Impacted Files	Coverage Δ
exporters/otlp/internal/transform/span.go	98.1% <ø> (ø)
exporters/otlp/otlpgrpc/driver.go	90.1% <100.0%> (ø)
exporters/otlp/otlphttp/driver.go	93.8% <100.0%> (ø)
exporters/otlp/otlpgrpc/connection.go	88.7% <0.0%> (+1.8%)	⬆️

[MrAlias]

The overall direction of that issues is to eventually move away from SpanSnapshot anyway. This will become wasted work. Closing.