Revert "Add verification to ensure we don't have redundant borrow scopes for @guaranteed forwarding phis"

This reverts commit dfbb2bd.

Author: meg-gupta

lib/SIL/Verifier/SILVerifier.cpp

@@ -4881,17 +4881,6 @@ class SILVerifier : public SILVerifierBase<SILVerifier> {
   }
 
   void checkBranchInst(BranchInst *BI) {
-    for (auto arg : BI->getArgs()) {
-      auto *borrow = dyn_cast<BeginBorrowInst>(arg);
-      if (!borrow) {
-        continue;
-      }
-      auto op = borrow->getOperand();
-      if (op->getOwnershipKind() != OwnershipKind::Guaranteed) {
-        continue;
-      }
-      assert(!isGuaranteedForwarding(op));
-    }
     require(BI->getArgs().size() == BI->getDestBB()->args_size(),
             "branch has wrong number of arguments for dest bb");
     require(std::equal(BI->getArgs().begin(), BI->getArgs().end(),