Clean up references to iiload, iistore, et al.

[hzongaro]

Once upon a time, the JIT compiler's opcodes had the letter i as a prefix if the operation was indirect — iiload, ibstore, and so on. Those opcodes were renamed to use the letter i as a suffix instead — iiload became iloadi, ilstore became istorei, etc.

Many comments and some trace code in the compiler — in both OpenJ9 and OMR — still refer to the old opcode names. For example, in Tree Simplifier and Inliner. It would be good to correct those lingering references to the old opcode names.