[ArgPromotion] Remove all the getters and ReplaceCallSite (NFC)

AARGetter is an abstraction over a source of the `AAResults` introduced
to support the legacy pass manager as well as the modern one. Since the
Argument Promotion pass doesn't support the legacy pass manager anymore,
the abstraction is not required and `AAResults` may be used directly.

The instance of the `FunctionAnalysisManager` is passed through the
functions to get all the required analyses just wherever they are
required and do not use the awkward getter callbacks.

The `ReplaceCallSite` parameter was required for the legacy pass manager
only and isn't used anymore, so the parameter has been eliminated.

Differential Revision: https://reviews.llvm.org/D128727