Revert "add -F and -X to default $LESS environment variable (#6611)"

This reverts commit 9544316e.

This setting broke mouse / touchpad scroll on programs using `less` output
due to it not using the alternate screen buffer.

Fixes #7025

lib/misc.zsh

@@ -20,7 +20,7 @@ setopt long_list_jobs
 
 ## pager
 env_default PAGER 'less'
-env_default LESS '-FRX'
+env_default LESS '-R'
 
 ## super user alias
 alias _='sudo'