Add KicBaseImage to existing config if missing (fixes v1.9.x upgrade)

[tstromberg]

Fixes docker: invalid reference format. which occurs in the following reproduction case:

minikube-1.9.2 start --driver=docker
docker stop minikube
docker rm minikube
minikube-1.12.0 start --driver=docker

For upgrades which require a container reset, we were inadvertently passing an empty cc.KicBaseImage to the resulting docker command-line.

[tstromberg]

/ok-to-test

[k8s-ci-robot]

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[minikube-pr-bot]

kvm2 Driver
docker Driver

[minikube-pr-bot]

kvm2 Driver
Times for minikube: [64.547466277 62.189983981000005 63.374132552999995]
Average time for minikube: 63.370527603666666

Times for Minikube (PR 8738): [62.089197214 65.106288707 66.44759319]
Average time for Minikube (PR 8738): 64.547693037

Averages Time Per Log

+--------------------------------+-----------+--------------------+
|              LOG               | MINIKUBE  | MINIKUBE (PR 8738) |
+--------------------------------+-----------+--------------------+
| * minikube v1.12.0 on Debian   |  0.055167 |           0.052590 |
|                           9.11 |           |                    |
| * Using the kvm2 driver based  |  0.018224 |           0.016868 |
| on existing profile            |           |                    |
| * Starting control plane node  |  0.011111 |           0.003014 |
| minikube in cluster minikube   |           |                    |
| * Creating kvm2 VM (CPUs=2,    | 41.030379 |          40.933682 |
| Memory=3700MB, Disk=20000MB)   |           |                    |
| ...                            |           |                    |
| * Preparing Kubernetes v1.18.3 | 20.776249 |          22.073946 |
| on Docker 19.03.12 ...         |           |                    |
| * Verifying Kubernetes         |  1.276552 |           1.240337 |
| components...                  |           |                    |
| * Enabled addons:              |  0.130624 |           0.144866 |
| default-storageclass,          |           |                    |
| storage-provisioner            |           |                    |
| * Done! kubectl is now         |  0.067499 |           0.078716 |
| configured to use "minikube"   |           |                    |
|                                |  0.004722 |           0.003674 |
+--------------------------------+-----------+--------------------+

docker Driver
Times for minikube: [24.16624929 25.709493386999995 25.306907223000003]
Average time for minikube: 25.0608833

Times for Minikube (PR 8738): [25.881317466 25.489330815 26.087785244]
Average time for Minikube (PR 8738): 25.819477841666668

Averages Time Per Log

+--------------------------------+-----------+--------------------+
|              LOG               | MINIKUBE  | MINIKUBE (PR 8738) |
+--------------------------------+-----------+--------------------+
| * minikube v1.12.0 on Debian   |  0.063713 |           0.064685 |
|                           9.11 |           |                    |
| * Using the docker driver      |  0.002428 |           0.002383 |
| based on existing profile      |           |                    |
| * Starting control plane node  |  0.056115 |           0.053643 |
| minikube in cluster minikube   |           |                    |
| * Creating docker container    |  7.243021 |           7.336470 |
| (CPUs=2, Memory=3700MB) ...    |           |                    |
| * Preparing Kubernetes v1.18.3 | 16.677051 |          17.338955 |
| on Docker 19.03.2 ...          |           |                    |
| * Verifying Kubernetes         |  0.785938 |           0.862108 |
| components...                  |           |                    |
| * Enabled addons:              |  0.167356 |           0.097080 |
| default-storageclass,          |           |                    |
| storage-provisioner            |           |                    |
| * Done! kubectl is now         |  0.061894 |           0.061149 |
| configured to use "minikube"   |           |                    |
|                                |  0.003367 |           0.003005 |
+--------------------------------+-----------+--------------------+