remove kubectl installation from Dockerfile (#447)

kubectl doesn't seem to be in use anywhere within the code, so removing
it from the Dockerfile should simplify the image creation and shrink
the image size somewhat

Signed-off-by: Kevin <kpostlet@redhat.com>

Author: KPostOffice

Dockerfile

@@ -10,15 +10,13 @@ COPY cmd cmd
 COPY pkg pkg
 COPY hack hack
 
-RUN cd /workdir && curl -LO https://storage.googleapis.com/kubernetes-release/release/$(curl -s https://storage.googleapis.com/kubernetes-release/release/stable.txt)/bin/linux/$(go env GOARCH)/kubectl && chmod +x kubectl
 ENV GO_BUILD_ARGS=$GO_BUILD_ARGS
 RUN echo "Go build args: $GO_BUILD_ARGS" && \
     make mcad-controller
 
 FROM registry.access.redhat.com/ubi8/ubi-minimal:latest
 
 COPY --from=BUILDER /workdir/_output/bin/mcad-controller /usr/local/bin
-COPY --from=BUILDER /workdir/kubectl /usr/local/bin
 
 RUN true \
     && microdnf update \