Revert "Copy helpers internally" again (#8494)

### Motivation:

Pull request #8476 was breaking SwiftPM builds in Xcode (i.e., the
_package resolution_ step):

<img
src="https://github.com/user-attachments/assets/2424e52c-1198-45c2-aa82-68c73ef5e9d6"
width=600/>

### Modifications:

This reverts commit 1d48e0a.

Author: pmattos

IntegrationTests/Tests/IntegrationTests/BasicTests.swift

@@ -94,7 +94,7 @@ private struct BasicTests {
     }
 
     @Test(
-        .skipHostOS(.windows, "'try!' expression unexpectedly raised an error: TSCBasic.Process.Error.missingExecutableProgram(program: \"which\")"),
+        .skipHostOS(.windows, "'try!' expression unexpectedly raised an error: TSCBasic.Process.Error.missingExecutableProgram(program: \"which\")")
     )
     func testSwiftCompiler() throws {
         try withTemporaryDirectory { tempDir in

Package.swift

@@ -725,7 +725,7 @@ let package = Package(
 
         // MARK: Additional Test Dependencies
 
-            .testTarget(
+            .target(
                 /** SwiftPM internal build test suite support library */
                 name: "_InternalBuildTestSupport",
                 dependencies: [
@@ -734,13 +734,12 @@ let package = Package(
                     "SwiftBuildSupport",
                     "_InternalTestSupport"
                 ],
-                path: "Sources/_InternalBuildTestSupport",
                 swiftSettings: [
                     .unsafeFlags(["-static"]),
                 ]
             ),
 
-        .testTarget(
+        .target(
             /** SwiftPM internal test suite support library */
             name: "_InternalTestSupport",
             dependencies: [
@@ -755,7 +754,6 @@ let package = Package(
                 .product(name: "OrderedCollections", package: "swift-collections"),
                 "Workspace",
             ],
-            path: "./Sources/_InternalTestSupport",
             swiftSettings: [
                 .unsafeFlags(["-static"]),
             ]

Sources/_InternalTestSupport/Process.swift

@@ -803,7 +803,7 @@ final class RegistryClientTests: XCTestCase {
         let availableManifests = try await registryClient.getAvailableManifests(
             package: identity,
             version: version,
-            observabilityScope: ObservabilitySystem.NOOP,
+            observabilityScope: ObservabilitySystem.NOOP
         )
 
         XCTAssertEqual(availableManifests["Package.swift"]?.toolsVersion, .v5_5)
@@ -3987,7 +3987,7 @@ extension RegistryClient {
             package: package.underlying,
             version: version,
             fileSystem: InMemoryFileSystem(),
-            observabilityScope: ObservabilitySystem.NOOP,
+            observabilityScope: ObservabilitySystem.NOOP
         )
     }