Remove DropAndReplace terminator

PR 107844 made DropAndReplace unused, let's remove it completely
from the codebase.

compiler/rustc_mir_build/src/build/custom/parse/instruction.rs

@@ -58,14 +58,6 @@ impl<'tcx, 'body> ParseCtxt<'tcx, 'body> {
                     unwind: None,
                 })
             },
-            @call("mir_drop_and_replace", args) => {
-                Ok(TerminatorKind::DropAndReplace {
-                    place: self.parse_place(args[0])?,
-                    value: self.parse_operand(args[1])?,
-                    target: self.parse_block(args[2])?,
-                    unwind: None,
-                })
-            },
             @call("mir_call", args) => {
                 let destination = self.parse_place(args[0])?;
                 let target = self.parse_block(args[1])?;