[RISCV] Remove legacy TA/TU pseudo distinction for binary instructions

This change continues with the line of work discussed in https://discourse.llvm.org/t/riscv-transition-in-vector-pseudo-structure-policy-variants/71295.

This change handles most of the binary pseudos. I excluded pseudos which _TIED variants, and those that produce mask results. Both a bit different in functionality, and deserve their own change and review. As with previous changes in the series, we replace the existing TA and TU forms with a single unified pseudo with a passthru (which may be implicit_def) and a policy operand.

As before, we see codegen changes (some improvements and some regressions) due to scheduling differences caused by the extra implicit_def instructions.

Differential Revision: https://reviews.llvm.org/D154245