add short lived header test

tests/suite/layout/grid/subheaders.typ

@@ -196,6 +196,55 @@
   ..([z],) * 4,
 )
 
+--- grid-subheaders-repeat-replace-short-lived ---
+#set page(height: 8em)
+#grid(
+  grid.header(
+    [a]
+  ),
+  grid.header(
+    level: 2,
+    [b]
+  ),
+  grid.header(
+    level: 2,
+    [c]
+  ),
+  grid.header(
+    level: 2,
+    [d]
+  ),
+  grid.header(
+    level: 2,
+    [e]
+  ),
+  grid.header(
+    level: 2,
+    [f]
+  ),
+  grid.header(
+    level: 2,
+    [g]
+  ),
+  grid.header(
+    level: 2,
+    [h]
+  ),
+  grid.header(
+    level: 2,
+    [i]
+  ),
+  grid.header(
+    level: 2,
+    [j]
+  ),
+  grid.header(
+    level: 3,
+    [k]
+  ),
+  ..([z],) * 10,
+)
+
 --- grid-subheaders-multi-page-row ---
 #set page(height: 8em)
 #grid(