Update trace API config creation functions

[MrAlias]

Follow our style guide and return the config struct instead of pointers. This will also allow a future change to address #2065 by updating the internal options interfaces.

[codecov]

Codecov Report

Merging #2212 (dfe67e9) into main (361a209) will increase coverage by 0.0%.
The diff coverage is 82.3%.

@@          Coverage Diff          @@
##            main   #2212   +/-   ##
=====================================
  Coverage   72.9%   72.9%           
=====================================
  Files        176     176           
  Lines      12161   12162    +1     
=====================================
+ Hits        8867    8868    +1     
  Misses      3055    3055           
  Partials     239     239           

Impacted Files	Coverage Δ
trace/config.go	63.7% <75.0%> (ø)
bridge/opentracing/internal/mock.go	67.0% <100.0%> (ø)
internal/global/trace.go	89.0% <100.0%> (+0.2%)	⬆️
sdk/trace/tracer.go	93.1% <100.0%> (ø)

[jmacd]

💯