docker: drop UPX (#2216)
docker: drop UPX (#2216)

This was intended to compress binaries to reduce the (already massive)
image a bit.

This comes at a cost - up to 1s per binary exec.

Docker images already have their own compression though. It turns out to
be actually *smaller* to just rely on this, surprisingly.

Most importantly, upx binaries seem to have intermittent issues where
they random exit with 127 (see
https://github.com/istio/istio/issues/41593, and various `kind` issues
that have plagued us for years).
istio/tools,istio/tools,istio/tools,istio/tools,istio/tools,istio/tools