Remove the WithDisabled option from Jaeger exporter

[MrAlias]

The WithDisabled option was added to support standard environment variables used by other Jaeger clients here. The goal was to add support for these environment variables to the extent that they make sense in the OpenTelemetry project.

Support for this environment variable, JAEGER_DISABLED, was removed here. This seems appropriate as exporter activation or deactivation is handled by registering or unregistering it with the TracerProvider, or, at an earlier phase of initialization, by using the no-op TracerProvider itself. Given there are already mechanisms to disable the export of the Jaeger exporter in OpenTelemetry it would make sense to remove this duplicate mechanism.

This removes the option that was added in parallel for the support of the environment variable.

Part of #1803

[codecov]

Codecov Report

Merging #1806 (ccc3465) into main (6867faa) will decrease coverage by 0.0%.
The diff coverage is n/a.

@@           Coverage Diff           @@
##            main   #1806     +/-   ##
=======================================
- Coverage   78.4%   78.3%   -0.1%     
=======================================
  Files        135     135             
  Lines       7249    7245      -4     
=======================================
- Hits        5686    5680      -6     
- Misses      1313    1315      +2     
  Partials     250     250             

Impacted Files	Coverage Δ
exporters/trace/jaeger/jaeger.go	91.0% <ø> (-0.2%)	⬇️
exporters/otlp/otlpgrpc/connection.go	90.6% <0.0%> (-1.9%)	⬇️