Revert "[bootstrap] Install swiftinterface instead of swiftmodule for PD"

[shahmishal]

Reverts #2355

To unblock CI, going to revert this commit.

19:03:14 /Users/buildnode/jenkins/workspace/oss-swift-incremental-RA-osx/buildbot_incremental/swiftpm-macosx-x86_64/x86_64-apple-macosx/release/swiftc --driver-mode=swift -L /Users/buildnode/jenkins/workspace/oss-swift-incremental-RA-osx/buildbot_incremental/swiftpm-macosx-x86_64/x86_64-apple-macosx/lib/swift/pm/4_2 -lPackageDescription -swift-version 4.2 -I /Users/buildnode/jenkins/workspace/oss-swift-incremental-RA-osx/buildbot_incremental/swiftpm-macosx-x86_64/x86_64-apple-macosx/lib/swift/pm/4_2 -target x86_64-apple-macosx10.10 -sdk /Applications/Xcode-beta.app/Contents/Developer/Platforms/MacOSX.platform/Developer/SDKs/MacOSX10.15.sdk -package-description-version 4.2 /Users/buildnode/jenkins/workspace/oss-swift-incremental-RA-osx/swiftpm/Package.swift -fileno 7
19:03:18 
/Users/buildnode/jenkins/workspace/oss-swift-incremental-RA-osx/swiftpm: error: manifest parse error(s):
19:03:18 Stack dump:
19:03:18 0.	Program arguments: /Users/buildnode/jenkins/workspace/oss-swift-incremental-RA-osx/buildbot_incremental/swift-macosx-x86_64/bin/swift -frontend -interpret /Users/buildnode/jenkins/workspace/oss-swift-incremental-RA-osx/swiftpm/Package.swift -target x86_64-apple-macosx10.10 -enable-objc-interop -sdk /Applications/Xcode-beta.app/Contents/Developer/Platforms/MacOSX.platform/Developer/SDKs/MacOSX10.15.sdk -I /Users/buildnode/jenkins/workspace/oss-swift-incremental-RA-osx/buildbot_incremental/swiftpm-macosx-x86_64/x86_64-apple-macosx/lib/swift/pm/4_2 -swift-version 4.2 -package-description-version 4.2 -module-name Package -lPackageDescription -- -fileno 7 
19:03:18 1.	Apple Swift version 5.1-dev (LLVM c5340df2d1, Swift 632399e0f8)
19:03:18 0  swift                    0x00000001050e6265 llvm::sys::PrintStackTrace(llvm::raw_ostream&) + 37
19:03:18 1  swift                    0x00000001050e52a8 llvm::sys::RunSignalHandlers() + 248
19:03:18 2  swift                    0x00000001050e6858 SignalHandler(int) + 264
19:03:18 3  libsystem_platform.dylib 0x00007fff5b36fb5d _sigtramp + 29
19:03:18 4  libsystem_platform.dylib 0x000000000000ffff _sigtramp + 2764702911
19:03:18 5  libsystem_platform.dylib 0x000000010d3a4264 _sigtramp + 2986559268
19:03:18 6  swift                    0x00000001014933b8 llvm::MCJIT::runFunction(llvm::Function*, llvm::ArrayRef<llvm::GenericValue>) + 456
19:03:18 7  swift                    0x0000000101496521 llvm::ExecutionEngine::runFunctionAsMain(llvm::Function*, std::__1::vector<std::__1::basic_string<char, std::__1::char_traits<char>, std::__1::allocator<char> >, std::__1::allocator<std::__1::basic_string<char, std::__1::char_traits<char>, std::__1::allocator<char> > > > const&, char const* const*) + 1313
19:03:18 8  swift                    0x0000000101488b51 swift::RunImmediately(swift::CompilerInstance&, std::__1::vector<std::__1::basic_string<char, std::__1::char_traits<char>, std::__1::allocator<char> >, std::__1::allocator<std::__1::basic_string<char, std::__1::char_traits<char>, std::__1::allocator<char> > > > const&, swift::IRGenOptions&, swift::SILOptions const&) + 3457
19:03:18 9  swift                    0x000000010147ecdd performCompileStepsPostSILGen(swift::CompilerInstance&, swift::CompilerInvocation&, std::__1::unique_ptr<swift::SILModule, std::__1::default_delete<swift::SILModule> >, bool, llvm::PointerUnion<swift::ModuleDecl*, swift::SourceFile*>, swift::PrimarySpecificPaths const&, bool, int&, swift::FrontendObserver*, swift::UnifiedStatsReporter*) + 2557
19:03:18 10 swift                    0x0000000101474138 performCompile(swift::CompilerInstance&, swift::CompilerInvocation&, llvm::ArrayRef<char const*>, int&, swift::FrontendObserver*, swift::UnifiedStatsReporter*) + 7032
19:03:18 11 swift                    0x0000000101471690 swift::performFrontend(llvm::ArrayRef<char const*>, char const*, void*, swift::FrontendObserver*) + 3024
19:03:18 12 swift                    0x0000000101418f49 main + 729
19:03:18 13 libdyld.dylib            0x00007fff5b1843d5 start + 1
19:03:18 --- bootstrap: error: build failed with exit status 1

[shahmishal]

Next build is blue - https://ci.swift.org/job/oss-swift-master-rebranch-incremental-RA-osx/494/console
https://ci.swift.org/job/oss-swift-incremental-RA-osx/8961/console