the xcode project file for debugserver exists only to make my
life easier when I'm working only on debugserver and don't need
to build the rest of llvm/lldb. It had many build configurations
to reflect our old lldb xcode project file, which is long gone.
Removing them to simplify the configurations.
Specifically dropping CustomSwift-Debug, DebugClang, DebugPresubmission,
CustomSwift-Release, BuildAndIntegration. Keeping Debug & Release.
7d67c06391