Revert "Support experimental test summary on non-Darwin (#6878)"

[compnerd]

This reverts commit ca45050.

Tests on Windows do not function after this change:

[388/392] Emitting module SwiftWin32PackageTests
C:\a\swift-build\swift-build\SourceCache\swift-win32\.build\x86_64-unknown-windows-msvc\debug\SwiftWin32PackageTests.derived\runner.swift:13:20: error: invalid escape sequence in literal

        return "C:\a\swift-build\swift-build\SourceCache\swift-win32\.build\x86_64-unknown-windows-msvc\debug\testOutput.txt"

[compnerd]

@swift-ci please smoke test

[neonichu]

The issue probably lies here:

var testOutputPath: String {
    return "\(buildParameters.testOutputPath)"
}

Maybe using ._nativePathString(escaped: true) would do the right thing?

[compnerd]

@swift-ci please smoke test

[neonichu]

@swift-ci please test

[neonichu]

We recently asked @shahmishal for aliasing "test" to "smoke test" but I guess this made "smoke test" non-functional except for Windows?

[tomerd]

@shahmishal @compnerd, @neonichu and myself were just chatting about windows CI for SwiftPM and not clear to us why it is only building and not running any of the tests (we were not involved in how it was set up). are we in a position to run the tests as well? this could helped avoid such rollback churn

[compnerd]

I'm going to merge this for now as this is actively blocking the use of SPM on Windows. Lets figure out how to get testing enabled to avoid this in the future.