Fix image centering in nuxeo-image-viewer after closing sidebar

When viewing a Picture document, the image found within the nuxeo-image-viewer element does not automatically center when the sidebar (containing details and metadata layout) is closed.

Steps To Reproduce:

1. Navigate to a Picture document in Web UI
2. Close the sidebar after the image preview loads using the  button

Expected result: the image preview center aligns relative to the new width of nuxeo-picture-view-layout (see behavior in LTS 2019)

Actual result: the image remains frozen at its previous location, while the controls toolbar center aligns as expected. The image only center aligns after the browser window size is changed.

(see attached video for reference)