Provide the default 'monolithic' version of executorConfigurations

In the move from gerrit/Blubber to GitLab, we'd not migrated the copy step of the images, so this file wasn't being created conditionally on the target environment, but instead left bare.

For now, let's just put the whole-hog file into place, so that the minted images work again, and we can revisit this later.

Change-Id: I6c294114aebeab4fecc62b0bc14d15890de377a6