Don't fuse inside computations that are already fused.
Don't fuse inside computations that are already fused.

FUTURE_COPYBARA_INTEGRATE_REVIEW=https://github.com/openxla/xla/pull/12979 from Tixxx:tixxx/pgle_send 469b2d31ff6b0270dda28f8754462681514d0e04
