Fix flaky tests (#1551)

Retry some assertions to fix following tests:

- `integration.restart_replication.test_suggestions`
- `integration.api_query.test_suggestions`

Author: rosik

test/integration/api_query_test.lua

@@ -119,6 +119,12 @@ g.before_all = function()
     end)
 end
 
+g.before_each(function()
+    helpers.retrying({}, function()
+        t.assert_equals(helpers.list_cluster_issues(g.cluster.main_server), {})
+    end)
+end)
+
 g.after_all = function()
     g.cluster:stop()
     g.server:stop()
@@ -674,8 +680,6 @@ end
 
 
 function g.test_issues()
-    t.assert_equals(helpers.list_cluster_issues(g.cluster.main_server), {})
-
     -----------------------------------------------------------------------------
     -- memory usage issues
     local server = g.cluster:server('storage')

test/integration/restart_replication_test.lua

@@ -38,12 +38,13 @@ function g.test_suggestion()
         message = "Replication from localhost:13302 (A-2)" ..
             " to localhost:13301 (A-1) isn't running",
     }
-
-    t.assert_equals(h.list_cluster_issues(g.A1), {replication_issue})
-    t.assert_items_equals(
-        h.get_suggestions(g.A1).restart_replication,
-        {{uuid = g.A1.instance_uuid}}
-    )
+    h.retrying({}, function()
+        t.assert_equals(h.list_cluster_issues(g.A1), {replication_issue})
+        t.assert_items_equals(
+            h.get_suggestions(g.A1).restart_replication,
+            {{uuid = g.A1.instance_uuid}}
+        )
+    end)
 
     g.A2.process:kill('STOP')
 
@@ -52,11 +53,13 @@ function g.test_suggestion()
 
     g.A2.process:kill('CONT')
 
-    t.assert_equals(h.list_cluster_issues(g.A1), {replication_issue})
-    t.assert_items_equals(
-        h.get_suggestions(g.A1).restart_replication,
-        {{uuid = g.A1.instance_uuid}}
-    )
+    h.retrying({}, function()
+        t.assert_equals(h.list_cluster_issues(g.A1), {replication_issue})
+        t.assert_items_equals(
+            h.get_suggestions(g.A1).restart_replication,
+            {{uuid = g.A1.instance_uuid}}
+        )
+    end)
 
     g.A1:graphql({
         query = [[
@@ -69,7 +72,7 @@ function g.test_suggestion()
         variables = {uuids = {g.A1.instance_uuid}}
     })
 
-    t.helpers.retrying({}, function()
+    h.retrying({}, function()
         t.assert_equals(h.list_cluster_issues(g.A1), {})
         t.assert_equals(h.get_suggestions(g.A1).restart_replication, nil)
     end)