Revert "Add current-scope/module instrs after arg receive"

This reverts commit 2fbbf6066d556dbcbf273be57a66b655d8347c65.

Conflicts:
	core/src/main/java/org/jruby/ir/IRBuilder.java

Because optional arguments need to be able to run code, we can't
move these loads later in the method body.
Add test case for reverted scope-load instruction moves.