[MemorySSA] Don't check def set when cloning memoryaccesses

For internal functions, globals-aa returns different ModRefInfo
results if they are inlined and are no longer called by external
functions. This causes an assertion failure when cloning memoryssa
accesses.

Fixes: https://github.com/llvm/llvm-project/issues/59546

Reviewed By: nikic

Differential Revision: https://reviews.llvm.org/D141185