Enable tests failing due to java-joda warnings (#42694) backport#42693

Tests were failing in mixed cluster after more broad warnings were
introduced in 6.x These tests were using `yyyy-MM-dd` pattern which
is now warning about the change of `y` to `u`. However, using predefined pattern
`strict_date` which uses the same format prevents the warning from being
generate and allow smooth upgrade/work in mixed cluster.
relates #42679

Author: pgomulka

rest-api-spec/src/main/resources/rest-api-spec/test/search.aggregation/230_composite.yml

@@ -262,7 +262,7 @@ setup:
                       "date_histogram": {
                         "field": "date",
                         "interval": "1d",
-                        "format": "yyyy-MM-dd"
+                        "format": "strict_date"
                       }
                     }
                   }
@@ -292,7 +292,7 @@ setup:
                         "date_histogram": {
                           "field": "date",
                           "interval": "1d",
-                          "format": "yyyy-MM-dd"
+                          "format": "strict_date"
                         }
                       }
                     }

rest-api-spec/src/main/resources/rest-api-spec/test/search/140_pre_filter_search_shards.yml

@@ -9,7 +9,7 @@ setup:
               properties:
                 created_at:
                    type: date
-                   format: "yyyy-MM-dd"
+                   format: "strict_date"
   - do:
       indices.create:
           index: index_2
@@ -20,7 +20,7 @@ setup:
               properties:
                 created_at:
                    type: date
-                   format: "yyyy-MM-dd"
+                   format: "strict_date"
   - do:
       indices.create:
           index: index_3
@@ -31,7 +31,7 @@ setup:
               properties:
                 created_at:
                    type: date
-                   format: "yyyy-MM-dd"
+                   format: "strict_date"
 
 
 ---