[LLVM][Transforms] Remove calls to pass initialization from pass constructors

[jurahul]

Many LLVM passes call their initializeXYZPass() from their constructors. As discussed in https://discourse.llvm.org/t/why-call-initializexyzpass-from-xyz-constructor/80692, this is not required, and pass initialization should ideally happen in one of the specific pass initialization functions (as a part of target initialization for target specific passes and one of the functions in InitializePasses.h for target independent passes).

This issue is to cleanup such initializations in pass constructors.