Unskip OpenTelemetry.Sampler.AWS tests related to Wiremock on .NET Fx

[Kielek]

Ref: wiremock/WireMock.Net#1368

Tests are failing on .NET Framework due to incompatibility in some dependency even with Minor/Patch fixes.

[Kielek]

@normj, @srprash,
WireMock.NET is only used by the Sampler.AWS package.
There is also decision to drop support for .NET Framework 4.6.2 in v2 wiremock/WireMock.Net#1359 (comment)

V1 brings security vulnerability, after bumping it basically not working in .NET Fx.

Could you please find some replacement for this package? If not possible, creating a local server should be fine for tests purposes.