Revert "[MemProf] Context disambiguation cloning pass [patch 1a/3]"

This reverts commit d6ad4f01.

Fails to build on at least gcc 12.2:

/home/npopov/repos/llvm-project/llvm/lib/Transforms/IPO/MemProfContextDisambiguation.cpp:482:1: error: no declaration matches ‘ContextNode<DerivedCCG, FuncTy, CallTy>* CallsiteContextGraph<DerivedCCG, FuncTy, CallTy>::getNodeForInst(const CallInfo&)’
  482 | CallsiteContextGraph<DerivedCCG, FuncTy, CallTy>::getNodeForInst(
      | ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
/home/npopov/repos/llvm-project/llvm/lib/Transforms/IPO/MemProfContextDisambiguation.cpp:393:16: note: candidate is: ‘CallsiteContextGraph<DerivedCCG, FuncTy, CallTy>::ContextNode* CallsiteContextGraph<DerivedCCG, FuncTy, CallTy>::getNodeForInst(const CallInfo&)’
  393 |   ContextNode *getNodeForInst(const CallInfo &C);
      |                ^~~~~~~~~~~~~~
/home/npopov/repos/llvm-project/llvm/lib/Transforms/IPO/MemProfContextDisambiguation.cpp:99:7: note: ‘class CallsiteContextGraph<DerivedCCG, FuncTy, CallTy>’ defined here
   99 | class CallsiteContextGraph {
      |       ^~~~~~~~~~~~~~~~~~~~