test: use alpine for gvsior image in testdata (#21059)

* use alpine for gvsior image in testdata

* remove dup copy leftover

test/integration/testdata/gvisor-addon-Dockerfile

@@ -12,9 +12,8 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
-FROM ubuntu:18.04
-RUN apt-get update && \
-    apt-get install -y kmod gcc wget xz-utils libc6-dev bc libelf-dev bison flex openssl libssl-dev libidn2-0 sudo libcap2 && \
-    rm -rf /var/lib/apt/lists/*
+# Need an image with chroot
+FROM alpine:3
+RUN apk -U add ca-certificates
 COPY gvisor-addon /gvisor-addon
 CMD ["/gvisor-addon"]