Revert "driver: Enable highlighting during isearch under zsh≥5.3."
Revert "driver: Enable highlighting during isearch under zsh≥5.3."

This reverts commit 4ad311ec0a6837b7c83bcfd1a1bf12cceb03f363.

danielshahaf/zsh-syntax-highlighting-debian,danielshahaf/zsh-syntax-highlighting-debian