Don’t include module name in test IDs

[ahoppen]

Determining the module name of a test in the syntactic test scanner requires us to get build settings, which can be slow while the build system generates the build graph. With #1662, I don’t think it’s necessary to include the module name in the test ID anymore to differentiate test suites with the same name in different modules.

[ahoppen]

Synced to Apple’s issue tracker as rdar://137886483

[ahoppen]

Looks like we can’t drop the module name because otherwise test classes become ambiguous if a test class with the same name is defined in two modules.

Eg.

Tests/MyLibraryTests/MyTests.swift

import XCTest

class MyTests: XCTestCase {
  func testMyLibrary() {}
}

Tests/MyLibraryTests2/MyTests2.swift

import XCTest

class MyTests: XCTestCase {
  func testMyLibrary() {}
}