Migrate usage of deprecated ServiceBus packages

[jviau]

Our tests use a deprecated service bus package:

azure-functions-host/test/WebJobs.Script.Tests.Integration/WebJobs.Script.Tests.Integration.csproj

Line 49 in 1bf0813

<PackageReference Include="Microsoft.Azure.ServiceBus" Version="4.2.1" />

However, it also appears that the actual .cs files which use that are excluded from compile:

azure-functions-host/test/WebJobs.Script.Tests.Integration/WebJobs.Script.Tests.Integration.csproj

Lines 24 to 28 in 1bf0813

	<Compile Remove="ScriptHostEndToEnd\ListenerFailureTests.cs" />
	<Compile Remove="ServiceBus\ServiceBusEndToEndTestBase.cs" />
	<Compile Remove="ServiceBus\ServiceBusTriggerCSharpEndToEndTests.cs" />
	<Compile Remove="ServiceBus\ServiceBusTriggerNodeEndToEndTests.cs" />
	<Compile Remove="Twilio\TwilioEndToEndTestsBase.cs" />

We should either migrate this package, fix the tests, and include them. Or remove the package and test files altogether.