Fix licence agreement tear down again! (#675)

https://eaflood.atlassian.net/browse/WATER-4336

Ok, we've made a bit of a hash with trying to [improve the tear-down speed](#671).

We realised in the rewrite we'd dropped a licence agreement DELETE statement that needed including so [fixed it](https://github.com/DEFRA/water-abstraction-system/pull/673/files).

Then we realised the tear-down was now faster but more flaky so [switched to the single query strategy](#674).

Only in the switch what do you know, we lost the licence agreement DELETE statement again.

Hopefully, for the last time, we fix this!

app/services/data/tear-down/water-schema.service.js

@@ -170,6 +170,14 @@ async function _deleteAllTestData () {
   WHERE
     "is_test" = TRUE;
 
+  DELETE
+  FROM
+    "water"."licence_agreements" AS "la"
+    USING "water"."licences" AS "l"
+  WHERE
+    "l"."is_test" = TRUE
+    AND "la"."licence_ref" = "l"."licence_ref";
+
   DELETE
   FROM
     "water"."financial_agreement_types"