wpt: Unskip the `css-tables suite (#31131)

This will be useful for tracking improvements to table support.

tests/wpt/meta/css/css-tables/tentative/caption.html.ini

@@ -0,0 +1,24 @@
+[caption.html]
+  [table 1]
+    expected: FAIL
+
+  [table 2]
+    expected: FAIL
+
+  [table 3]
+    expected: FAIL
+
+  [table 6]
+    expected: FAIL
+
+  [table 7]
+    expected: FAIL
+
+  [table 8]
+    expected: FAIL
+
+  [table 9]
+    expected: FAIL
+
+  [table 10]
+    expected: FAIL