Remove RawSpan workaround

[iCharlesHu]

Currently the following snippet causes a crash during LifetimeDependenceScopeFixup:

                do {
                    switch result {
                    case .success(let data):
                        let output = try self.output(from: data.bytes) // <— `data.bytes` returns a `RawSpan`
                        try readFd.close()
                        continuation.resume(returning: output)
                    case .failure(let error):
                        try readFd.close()
                        continuation.resume(throwing: error)
                    }
                } catch {
                    try? readFd.close()
                    continuation.resume(throwing: error)
                }

We put in a workaround. This issue tracks the removal for these workarounds once the compiler fixes are merged.

[glessard]

swiftlang/swift#80880 should have fixed this in the 6.2 branch of the compiler.
That should be included as of swiftlang-6.2.0.9.