CI: Linux + 6.2 builds are broken with duplicated symbol issues when prebuilt swift-syntax is used

[ktoso]

/usr/bin/ld.gold: /__w/swift-java/swift-java/.build/x86_64-unknown-linux-gnu/debug/SwiftDiagnostics-tool.build/FixIt.swift.o: previous definition here
/usr/bin/ld.gold: error: /__w/swift-java/swift-java/.build/prebuilts/swift-syntax/602.0.0/swift-6.2-RELEASE-MacroSupport-ubuntu_jammy_x86_64/lib/libMacroSupport.a(FixIt.swift.o): multiple definition of '$s16SwiftDiagnostics5FixItVN'
/usr/bin/ld.gold: /__w/swift-java/swift-java/.build/x86_64-unknown-linux-gnu/debug/SwiftDiagnostics-tool.build/FixIt.swift.o: previous definition here
/usr/bin/ld.gold: error: /__w/swift-java/swift-java/.build/prebuilts/swift-syntax/602.0.0/swift-6.2-RELEASE-MacroSupport-ubuntu_jammy_x86_64/lib/libMacroSupport.a(FixIt.swift.o): multiple definition of '$s16SwiftDiagnostics5FixItV6ChangeON'
/usr/bin/ld.gold: /__w/swift-java/swift-java/.build/x86_64-unknown-linux-gnu/debug/SwiftDiagnostics-tool.build/FixIt.swift.o: previous definition here
/usr/bin/ld.gold: error: /__w/swift-java/swift-java/.build/prebuilts/swift-syntax/602.0.0/swift-6.2-RELEASE-MacroSupport-ubuntu_jammy_x86_64/lib/libMacroSupport.a(IfConfigDecl+IfConfig.swift.o): multiple definition of '$s11SwiftSyntax012IfConfigDeclB0V0acD0E12activeClause2inAA0cdgB0VSg6clause_Say0A11Diagnostics10DiagnosticVG11diagnosticstx_tAD18BuildConfigurationRzlF'
/usr/bin/ld.gold: /__w/swift-java/swift-java/.build/x86_64-unknown-linux-gnu/debug/SwiftIfConfig-tool.build/IfConfigDecl+IfConfig.swift.o: previous definition here
clang: error: linker command failed with exit code 1 (use -v to see invocation)
[1425/1426] Linking swift-javaPackageTests.xctest
Error: Process completed with exit code 1.

Which is rather weird because all we're doing is just a plain old swiftly installation...

[ktoso]

This will be fixed by swiftlang/swift-package-manager#9331

Until then, we cannot use prebuilt swift syntax.

This is a general swiftpm issue, we just happened to bump into it.