ogcp.js: fix images selector in "images" section

Any operation inside "Images" view fails with error message 'missing
"image-server" key'. Operations under images view section are loading
image info and "delete image".

Previously, a hidden checkbox entry was added to support multiple
ogServer images entries. This hidden checkbox value holds the
corresponding ogServer address of some image list. This hidden
'image-server' checkbox is checked or unchecked whenever some visible
image from this server is checked in the list by the user.

Commit 70eb7389bb introduces checkImageServer javascript function that
mainly attaches an onchange event to each image checkbox so that
checking or unchecking it updates the hidden 'image-server' checkboxes
holding the ogserver address associated with each ogserver entry list.

When loading "Images" view each configured ogServer entry is collapsed
(thus each image checkbox is hidden). The current selector is ignoring
hidden checkboxes and thus checkImageServer is unable to attach the
necessary onchange event to each image checkbox.

The hidden 'image-server' checkbox is always hidden and does not need
attaching any onchange event. Fix selector by not ignoring hidden
elements and omitting any checkbox with name 'image-server'.

Fixes: 70eb7389bb ("Add ogServer parameter to imagesForm")

ogcp/static/js/ogcp.js

@@ -293,7 +293,7 @@ function RemovePartition(evt) {
 }
 
 function checkImageServer() {
-    const images = $('input:checkbox[form|="imagesForm"]:not(:hidden)')
+    const images = $('input:checkbox[form|="imagesForm"][name!="image-server"]')
 
     images.on('change', function() {
         const selectedServer = $('#' + $.escapeSelector(this.dataset.server));