test(alerting): align AlertEvaluatorJobIT CH cleanup with house style

Replace async @AfterEach ALTER...DELETE with @BeforeEach TRUNCATE TABLE
executions — matches the convention used in ClickHouseExecutionStoreIT
and peers. Env-slug isolation was already preventing cross-test pollution;
this change is about hygiene and determinism (TRUNCATE is synchronous).

cameleer-server-app/src/test/java/com/cameleer/server/app/alerting/eval/AlertEvaluatorJobIT.java

@@ -54,6 +54,13 @@ class AlertEvaluatorJobIT extends AbstractPostgresIT {
 
     @BeforeEach
     void setup() {
+        // ClickHouse — purge any executions left over from prior tests in the
+        // shared CH instance. Matches the house-style used across the CH IT
+        // suite (see ClickHouseExecutionStoreIT, ClickHouseStatsStoreIT, etc.).
+        // TRUNCATE is synchronous, unlike ALTER ... DELETE (mutations_sync=0).
+        clickHouseJdbc.execute("TRUNCATE TABLE executions");
+        clickHouseJdbc.execute("TRUNCATE TABLE processor_executions");
+
         // Default: empty registry — all evaluators return Clear
         when(agentRegistryService.findAll()).thenReturn(List.of());
 
@@ -91,13 +98,7 @@ class AlertEvaluatorJobIT extends AbstractPostgresIT {
         jdbcTemplate.update("DELETE FROM alert_rules WHERE environment_id = ?", envId);
         jdbcTemplate.update("DELETE FROM environments WHERE id = ?", envId);
         jdbcTemplate.update("DELETE FROM users WHERE user_id = ?", SYS_USER);
-        // ClickHouse — purge any executions seeded into this env. The shared CH instance
-        // persists across tests in the suite; scope the wipe to this test's env slug.
-        try {
-            if (envSlug != null) {
-                clickHouseJdbc.execute("ALTER TABLE executions DELETE WHERE environment = '" + envSlug + "'");
-            }
-        } catch (Exception ignored) { /* best-effort; next setup uses a fresh env slug */ }
+        // ClickHouse `executions` is truncated in @BeforeEach (house style).
     }
 
     // -------------------------------------------------------------------------