Revert "[DebugInfo][RemoveDIs] Turn on non-instrinsic debug-info by default"

This reverts commit bdde5f9.

Two situations that are tripping a few buildbots:

  https://lab.llvm.org/buildbot/#/builders/205/builds/25126

Here, polly is currently presenting a DebugLoc attached to a debugging
intrinsic as a "true" source location in a user report, something that's
unreliable.

  https://lab.llvm.org/buildbot/#/builders/184/builds/10242

These HWAsan failures are probably (97% confidence) because in
StackInfoBuilder::visit we're not observing DPValues attached to lifetime
intrinsics because they're delt with higher up the function.

But it's late-o'clock here, so revert for now.

Author: jmorse

llvm/lib/IR/BasicBlock.cpp

@@ -34,7 +34,7 @@ cl::opt<bool>
     UseNewDbgInfoFormat("experimental-debuginfo-iterators",
                         cl::desc("Enable communicating debuginfo positions "
                                  "through iterators, eliminating intrinsics"),
-                        cl::init(true));
+                        cl::init(false));
 
 DPMarker *BasicBlock::createMarker(Instruction *I) {
   assert(IsNewDbgInfoFormat &&