Fix trx parsing in test.ps1 to handle hierarchical changes from MSTest V2 1.3.2

[smadala]

Description

• Stdout and Stderror of failed tests of vstest repo not showing up on console.

Steps to reproduce

• Update MSTest v2 version to 1.3.2 here
• Run test.ps1 with some failing tests.

Expected behavior

• All the standard output and error message should be displayed like below.

22:57:24 ... .. .. . 1. Microsoft.TestPlatform.AcceptanceTests.DiscoveryTests.DiscoverTestsShouldShowProperWarningIfNoTestsOnTestCaseFilter (RunnerFramework = netcoreapp2.0, TargetFramework = netcoreapp1.0, InProcess)
22:57:24 ... .. .. .. .ErrorMessage: 
22:57:24 StringAssert.Contains failed. String 'Microsoft (R) Test Execution Command Line Tool Version 15.8.0-dev Copyright (c) Microsoft Corporation. All rights reserved. The following Tests are available: Warning: No test is available for testcase filter `NonExistTestCaseName` in D:\j\workspace\Windows_NT_Re---eafdf36b\test\TestAssets\SimpleTestProject2\bin\Release\netcoreapp1.0\SimpleTestProject2.dll ' does not contain string 'Warning: No test available for testcase filter `NonExistTestCaseName` in'. .
22:57:24 ... .. .. .. .StackTrace: 
22:57:24    at Microsoft.TestPlatform.AcceptanceTests.DiscoveryTests.DiscoverTestsShouldShowProperWarningIfNoTestsOnTestCaseFilter(RunnerInfo runnerInfo)
22:57:24 
22:57:24 ... .. .. .. .StdOut: 
22:57:24 IntegrationTestBase.Execute: Starting vstest.console.exe
22:57:24 IntegrationTestBase.Execute: Path = D:\j\workspace\Windows_NT_Re---eafdf36b\tools\dotnet\dotnet.exe
22:57:24 IntegrationTestBase.Execute: Arguments = "D:\j\workspace\Windows_NT_Re---eafdf36b\artifacts\Release\netcoreapp2.0\vstest.console.dll" "D:\j\workspace\Windows_NT_Re---eafdf36b\test\TestAssets\SimpleTestProject2\bin\Release\netcoreapp1.0\SimpleTestProject2.dll" /testadapterpath:"D:\j\workspace\Windows_NT_Re---eafdf36b\packages\MSTest.TestAdapter\1.3.1\build\_common" /logger:"console;verbosity=normal" /listtests /testcasefilter:NonExistTestCaseName /logger:"console;prefix=true"
22:57:24 IntegrationTestBase.Execute: stdError = 
22:57:24 
22:57:24 IntegrationTestBase.Execute: stdOut = Microsoft (R) Test Execution Command Line Tool Version 15.8.0-dev
22:57:24 Copyright (c) Microsoft Corporation.  All rights reserved.
22:57:24 
22:57:24 The following Tests are available:
22:57:24 Warning: No test is available for testcase filter `NonExistTestCaseName` in D:\j\workspace\Windows_NT_Re---eafdf36b\test\TestAssets\SimpleTestProject2\bin\Release\netcoreapp1.0\SimpleTestProject2.dll
22:57:24 
22:57:24 
22:57:24 IntegrationTestBase.Execute: Stopped vstest.console.exe. Exit code = 0

Actual behavior

More details

https://github.com/Microsoft/vstest/pull/1656/files#r197683145

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Probably no longer relevant.