SIL: use Test for the SmallProjectionPath's unit tests

Now that we have `Test` available in the SIL module, we can use it for the SmallProjectionPath's unit tests and get rid of the RunUnitTests pass.

Author: eeckstein

SwiftCompilerSources/Sources/Optimizer/PassManager/PassRegistration.swift

@@ -150,7 +150,6 @@ private func registerSwiftPasses() {
   registerPass(deadEndBlockDumper, { deadEndBlockDumper.run($0) })
   registerPass(memBehaviorDumper, { memBehaviorDumper.run($0) })
   registerPass(rangeDumper, { rangeDumper.run($0) })
-  registerPass(runUnitTests, { runUnitTests.run($0) })
   registerPass(testInstructionIteration, { testInstructionIteration.run($0) })
   registerPass(updateBorrowedFromPass, { updateBorrowedFromPass.run($0) })
 }

SwiftCompilerSources/Sources/Optimizer/TestPasses/CMakeLists.txt

@@ -15,7 +15,6 @@ swift_compiler_sources(Optimizer
   MemBehaviorDumper.swift
   SILPrinter.swift
   RangeDumper.swift
-  RunUnitTests.swift
   UpdateBorrowedFrom.swift
   TestInstructionIteration.swift
 )