[lit] Apply a different label for tests under validation-test/ than the ones under test/

[lorentey]

This will let us find the test file that produced a failure on the first attempt, saving the project at least three trillion cumulative person-seconds each year. 🙃

[lorentey]

@swift-ci test

[swift-ci]

Build failed
Swift Test OS X Platform
Git Sha - 8c3a8e7

[lorentey]

21:14:25 Test Suite 'Selected tests' started at 2021-11-11 21:12:38.990
21:14:25 Test Suite 'SwiftPMPackageTests.xctest' started at 2021-11-11 21:12:38.991
21:14:25 Test Suite 'PackageCollectionsStorageTests' started at 2021-11-11 21:12:38.991
21:14:25 Test Case '-[PackageCollectionsTests.PackageCollectionsStorageTests testListNonBatching]' started.
21:14:25 
21:14:25 Exited with signal code 6

[lorentey]

@swift-ci test macOS platform

[swift-ci]

Build failed
Swift Test OS X Platform
Git Sha - 8c3a8e7

[lorentey]

13:24:59 /Users/buildnode/jenkins/workspace/swift-PR-macos/branch-main/swift-docc/Sources/SwiftDocC/Infrastructure/Symbol Graph/SymbolGraphRelationshipsBuilder.swift:145:45: error: referencing operator function '==' on 'StringProtocol' requires that 'SymbolGraph.Symbol.KindIdentifier' conform to 'StringProtocol'
13:24:59         if conformingSymbol.kind.identifier == SymbolGraph.Symbol.Kind.Swift.protocol.rawValue {
13:24:59                                             ^
13:24:59 Swift.StringProtocol:1:11: note: where 'Self' = 'SymbolGraph.Symbol.KindIdentifier'
13:24:59 extension StringProtocol {
13:24:59           ^
13:24:59 /Users/buildnode/jenkins/workspace/swift-PR-macos/branch-main/swift-docc/Sources/SwiftDocC/Infrastructure/Symbol Graph/SymbolGraphRelationshipsBuilder.swift:152:81: error: referencing operator function '==' on 'StringProtocol' requires that 'SymbolGraph.Symbol.KindIdentifier' conform to 'StringProtocol'
13:24:59             if let rawSymbol = conformingNode.symbol, rawSymbol.kind.identifier == SymbolGraph.Symbol.Kind.Swift.protocol.rawValue {
13:24:59                                                                                 ^
13:24:59 Swift.StringProtocol:1:11: note: where 'Self' = 'SymbolGraph.Symbol.KindIdentifier'
13:24:59 extension StringProtocol {
13:24:59           ^

[lorentey]

@swift-ci smoke test macOS platform

[lorentey]

It looks like the DocC build issue was resolved by swiftlang/swift-docc#30.