PHP7.2 image is not valid under "wp scaffold plugin-tests" command

[shahariaazam]

It seems that tetraweb/php:7.2 is not a valid image anymore. So we should remove this for GitLab CI script.

Runtime platform      arch=amd64 os=linux pid=749 revision=4c96e5ad version=12.9.0
WARNING: You most probably have uncommitted changes. 
WARNING: These changes will not be tested.         
Running with gitlab-runner 12.9.0 (4c96e5ad)
Preparing the "docker" executor
Using Docker executor with image tetraweb/php:7.2 ...
Starting service mysql:5.6 ...
Pulling docker image mysql:5.6 ...
Using docker image sha256:c8078e8ab06d8dabd6c30cffb03951fa035d85f75c19a83ace29b01cb3ecd272 for mysql:5.6 ...
Waiting for services to be up and running...
Pulling docker image tetraweb/php:7.2 ...
ERROR: Job failed: Error response from daemon: manifest for tetraweb/php:7.2 not found: manifest unknown: manifest unknown (docker.go:196:3s)
FATAL: Error response from daemon: manifest for tetraweb/php:7.2 not found: manifest unknown: manifest unknown (docker.go:196:3s) 

We can also follow the similar issue related to php7.2 on TetraWeb/docker#60

[mvhirsch]

Looks like a duplicate of #239

[swissspidy]

Indeed, closing as duplicate of #239