simplify plotGrid, add cancel to metricSelect, improve metricPlot render logic

web/frontend/src/generic/PlotGrid.svelte

@@ -4,7 +4,6 @@
     Properties:
     - `itemsPerRow Number`: Elements to render per row
     - `items [Any]`: List of plot components to render
-    - `renderFor String`:   If 'job', filter disabled metrics
  -->
 
  <script>
@@ -15,43 +14,13 @@
 
     export let itemsPerRow
     export let items
-    export let renderFor
-
-    let rows = [];
-    const isPlaceholder = x => x._is_placeholder === true;
-
-    function tile(items, itemsPerRow) {
-        const rows = []
-        for (let ri = 0; ri < items?.length; ri += itemsPerRow) {
-            const row = []
-            for (let ci = 0; ci < itemsPerRow; ci += 1) {
-                if (ri + ci < items?.length)
-                    row.push(items[ri + ci])
-                else
-                    row.push({ _is_placeholder: true, ri, ci })
-            }
-            rows.push(row)
-        }
-        return rows
-    }
-
-    $: if (renderFor === 'job') {
-        rows = tile(items.filter(item => item.disabled === false), itemsPerRow)
-    } else {
-        rows = tile(items, itemsPerRow)
-    }
-
 </script>
 
-{#each rows as row}
-  <Row cols={{ xs: 1, sm: 1, md: 2, lg: itemsPerRow}}>
-    {#each row as item (item)}
-      <Col class="px-1">
-        {#if !isPlaceholder(item)}
-          <slot item={item}/>
-        {/if}
-      </Col>
-    {/each}
-  </Row>
-{/each}
+<Row cols={{ xs: 1, sm: 2, md: 3, lg: itemsPerRow}}>
+  {#each items as item}
+    <Col class="px-1">
+      <slot {item}/>
+    </Col>
+  {/each}
+</Row>