[lldb] [Utility] Remove Status::WasInterrupted() along with its only use

Remove Status::WasInterrupted() that checks whether the underlying error
code matches EINTR.  ProcessGDBRemote::ConnectToDebugserver() is its
only call site, and it does not seem correct there.  After all, EINTR
is precisely when we want to retry, not stop retrying.  Furthermore,
it should not really matter since we should be catching EINTR
immediately via llvm::sys::RetryAfterSignal() but that's another story.

Differential Revision: https://reviews.llvm.org/D111908