Copy preview images and thumbnails to the central store

[stscijgbot-jwql]

Issue JWQL-262 was created on JIRA by Bryan Hilbert:

With the setup details for the new RHEL9 jwql servers, the web server will be hosted on a different machine than that which runs the preview image generation. Currently, those tasks are both done on the same machine, and results are saved on that machine. Once those jobs are split between different machines, which can't see into each others' internal directories, the web server will no longer be able to grab the preview images. 

So we need to move the preview images and thumbnails somewhere that the monitor-running machine can save files, and the web server can see the files. Central store is the obvious answer here.

We need to copy the files over, and then update the config files on the new machines to tell them where to find the preview images.