[mlir][linalg][bufferize] Remove redundant methods from op interface

These two methods are redundant and removed:
* `bufferizesToAliasOnly`: If not `bufferizesToMemoryRead` and not `bufferizesToMemoryWrite` but `getAliasingOpResult` returns a non-null value, we know that this OpOperand is alias-only. This method now has a default implementation and does not have to be implemented.
* `getInplaceableOpResult`: The analysis does not differentiate between "inplaceable" and "aliasing". The only thing that matters is whether or not OpOperand and OpResult are aliasing. That is the key property that makes buffer copies necessary.

Differential Revision: https://reviews.llvm.org/D112902