insane.bbclass: remove leftover variables and comment

The code that used these variable and the comment was introduced in
commit b44d32ef ("insane.bbclass: Portions of code were not running,
fix this and sync with OE.dev. Also add tests for bad sysroot rpaths in
binaries"). Later, in commit 17dae13f ("insane.bbclass: Fix ELF
bitsize comparison"), some of that code was removed again, but not the
variables and the comment.

Signed-off-by: Emil Kronborg <emil.kronborg@protonmail.com>
Signed-off-by: Alexandre Belloni <alexandre.belloni@bootlin.com>
(cherry picked from commit 730d00b0)
Signed-off-by: Steve Sakoman <steve@sakoman.com>