generator/linux: copyTargetSwiftFromDocker does not need to call copyTargetSwift (#160)

copyTargetSwiftFromDocker() already copies all the same files as copyTargetSwift,
and puts them in the destination directory.   Calling copyTargetSwift() at the
end just results in several pointless rsync calls which sync the directories to
themselves.

Stopping in copyTargetSwift() shows that the source and destination arguments
point to the same place:

    Process 77272 stopped
    * thread #2, queue = 'com.apple.root.default-qos.cooperative', stop reason = breakpoint 1.1
        frame #0: ... at SwiftSDKGenerator+Copy.swift:105:8
       102      }
       103    }
       104
    -> 105    func copyTargetSwift(from distributionPath: FilePath, sdkDirPath: FilePath) async throws {
       106      logGenerationStep("Copying Swift core libraries for the target triple into Swift SDK bundle...")
       107
       108      for (pathWithinPackage, pathWithinSwiftSDK) in [
    Target 0: (swift-sdk-generator) stopped.
    (lldb) print distributionPath.string
    (String) ".../ubuntu-jammy.sdk/usr"
    (lldb) print sdkDirPath.string
    (String) ".../ubuntu-jammy.sdk"

The first rsync command line is then:

    rsync -a .../ubuntu-jammy.sdk/usr/lib/swift .../ubuntu-jammy.sdk/usr/lib

Removing the call to copyTargetSwift() does not save much time because rsync
does not do much work, however disentangling the Ubuntu-based SDK build from
the container-based build makes it easier to refactor both of them independently.

Diffing SDKs built before and after this change shows them to be identical.
The EndToEndTests (which currently can't be run by CI) continue to pass locally.

Author: euanh

Sources/SwiftSDKGenerator/Generator/SwiftSDKGenerator+Copy.swift

@@ -97,7 +97,6 @@ extension SwiftSDKGenerator {
         try await generator.removeRecursively(at: sdkUsrLibPath.appending("python3.10"))
 
         try await generator.removeRecursively(at: sdkUsrLibPath.appending("ssl"))
-        try await generator.copyTargetSwift(from: sdkUsrPath, sdkDirPath: sdkDirPath)
       }
     }
   }