remove FormatException in tests and docs (part2)

[TimothyMothra]

Fixes #3690.

Follow up to PR #4095

Changes

• reenable tests disabled in previous PR.
• cleanup tests to assert default value after setting an invalid value for Environment Variables.
• cleanup docs.

Please provide a brief description of the changes here.

For significant contributions please make sure you have completed the following items:

• Appropriate CHANGELOG.md updated for non-trivial changes
• Design discussion issue #
• Changes in public API reviewed

[codecov]

Codecov Report

Merging #4099 (112008d) into main (03af717) will increase coverage by 0.08%.
The diff coverage is n/a.

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #4099      +/-   ##
==========================================
+ Coverage   85.46%   85.55%   +0.08%     
==========================================
  Files         292      292              
  Lines       11306    11306              
==========================================
+ Hits         9663     9673      +10     
+ Misses       1643     1633      -10     

Impacted Files	Coverage Δ
...Telemetry.Exporter.Jaeger/JaegerExporterOptions.cs	100.00% <ø> (ø)
...orter.OpenTelemetryProtocol/OtlpExporterOptions.cs	100.00% <ø> (ø)
...Telemetry.Exporter.Zipkin/ZipkinExporterOptions.cs	100.00% <ø> (ø)
...metry/Trace/BatchExportActivityProcessorOptions.cs	100.00% <ø> (ø)
...ter.ZPages/Implementation/ZPagesActivityTracker.cs	100.00% <0.00%> (+2.85%)	⬆️
...emetry.Api/Internal/OpenTelemetryApiEventSource.cs	82.35% <0.00%> (+5.88%)	⬆️
.../OpenTelemetry/Internal/ConfigurationExtensions.cs	100.00% <0.00%> (+12.50%)	⬆️
...Propagators/OpenTelemetryPropagatorsEventSource.cs	100.00% <0.00%> (+12.50%)	⬆️