Remove propagation testing types from oteltest

[MrAlias]

The only place I can find these types being referenced here or in the contrib repo is in the internal/global package. Move these types internal and deprecate the exported versions. This removes the last oteltest dependency the otel package has after #2111 and is a part of #2077.

[codecov]

Codecov Report

Merging #2116 (bd6a432) into main (25d739b) will increase coverage by 0.1%.
The diff coverage is 75.6%.

@@           Coverage Diff           @@
##            main   #2116     +/-   ##
=======================================
+ Coverage   73.1%   73.2%   +0.1%     
=======================================
  Files        165     167      +2     
  Lines       8155    8237     +82     
=======================================
+ Hits        5965    6035     +70     
- Misses      1961    1971     +10     
- Partials     229     231      +2     

Impacted Files	Coverage Δ
oteltest/text_map_propagator.go	76.2% <ø> (ø)
internal/internaltest/text_map_carrier.go	73.0% <73.0%> (ø)
internal/internaltest/text_map_propagator.go	80.0% <80.0%> (ø)
sdk/metric/sdk.go	83.7% <0.0%> (+3.4%)	⬆️
sdk/metric/refcount_mapped.go	100.0% <0.0%> (+22.2%)	⬆️