Replace iostat with sysstat package

which includes iostat, pidstat, and other performance tools.

Ref: https://git.busybox.net/buildroot/tree/package/sysstat/Config.in?id=3bbf1c2ea6140d8b288b0af5b1a9c3a1aa92edad

deploy/iso/minikube-iso/configs/minikube_defconfig

@@ -60,5 +60,5 @@ BR2_TARGET_ROOTFS_ISO9660_BOOT_MENU="$(BR2_EXTERNAL_MINIKUBE_PATH)/board/coreos/
 BR2_TARGET_SYSLINUX=y
 BR2_PACKAGE_HOST_E2TOOLS=y
 BR2_PACKAGE_SYSTEMD_TIMESYNCD=y
-BR2_PACKAGE_IOSTAT=y
 BR2_PACKAGE_STRACE=y
+BR2_PACKAGE_SYSSTAT=y