SQL Expressions: Replace NaN/Inf values with Null (#112641)

This is because MySQL doesn't support storing of NaN valuels, and therefore go-mysql-server isn't going to either.

Float fields/columns are always mapped to be nullable now, otherwise we would have to replace NaN/Inf with 0.

pkg/registry/apis/query/testdata/prometheus_with_sql_expression.json

@@ -13,7 +13,7 @@
                 "type": "number",
                 "typeInfo": {
                   "frame": "float64",
-                  "nullable": false
+                  "nullable": true
                 }
               }
             ]