remove test pem files

Dockerfile

@@ -62,6 +62,7 @@ RUN mkdir -p /usr/local/nginx/sbin && \
     ln -s /usr/lib/libc.so.6 /usr/lib/libc.musl-x86_64.so.1 && \
     chown --from=998:nginx nginx:nginx * -R && \
     chown -R nginx:nginx /etc/nginx && \
+    rm -rf /etc/nginx/lua/test/fixtures/default-cert.pem /etc/nginx/lua/test/fixtures/example-com-cert.pem && \
     dnf clean all && \
     rm -rf /var/cache/dnf /tmp/*.tar.gz /etc/nginx/musl-1.2.2 /etc/nginx/out