Hide format filter and column for system projects

System projects like _pypi only contain packages of one format,
so the format filter dropdown and column are redundant.

frontend/src/pages/ProjectPage.tsx

@@ -294,18 +294,20 @@ function ProjectPage() {
           placeholder="Filter packages..."
           className="list-controls__search"
         />
-        <select
-          className="list-controls__select"
-          value={format}
-          onChange={(e) => handleFormatChange(e.target.value)}
-        >
-          <option value="">All formats</option>
-          {FORMAT_OPTIONS.map((f) => (
-            <option key={f} value={f}>
-              {f}
-            </option>
-          ))}
-        </select>
+        {!project?.is_system && (
+          <select
+            className="list-controls__select"
+            value={format}
+            onChange={(e) => handleFormatChange(e.target.value)}
+          >
+            <option value="">All formats</option>
+            {FORMAT_OPTIONS.map((f) => (
+              <option key={f} value={f}>
+                {f}
+              </option>
+            ))}
+          </select>
+        )}
       </div>
 
       {hasActiveFilters && (
@@ -341,11 +343,11 @@ function ProjectPage() {
               className: 'cell-description',
               render: (pkg) => pkg.description || '—',
             },
-            {
+            ...(!project?.is_system ? [{
               key: 'format',
               header: 'Format',
-              render: (pkg) => <Badge variant="default">{pkg.format}</Badge>,
-            },
+              render: (pkg: Package) => <Badge variant="default">{pkg.format}</Badge>,
+            }] : []),
             {
               key: 'tag_count',
               header: 'Tags',