Fix flaky test in range aggregation yaml test (opensearch-project#14486)

Signed-off-by: bowenlan-amzn <bowenlan23@gmail.com>

Author: bowenlan-amzn

rest-api-spec/src/main/resources/rest-api-spec/test/search.aggregation/10_histogram.yml

@@ -678,6 +678,11 @@ setup:
           - '{"index": {}}'
           - '{"date": "2016-03-01"}'
 
+  - do:
+      indices.forcemerge:
+        index: test_2
+        max_num_segments: 1
+
   - do:
       search:
         index: test_2

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

@@ -1101,6 +1101,12 @@ setup:
           - '{"date": "2016-02-01"}'
           - '{"index": {}}'
           - '{"date": "2016-03-01"}'
+
+  - do:
+      indices.forcemerge:
+        index: test_2
+        max_num_segments: 1
+
   - do:
       search:
         index: test_2

rest-api-spec/src/main/resources/rest-api-spec/test/search.aggregation/330_auto_date_histogram.yml

@@ -133,6 +133,11 @@ setup:
           - '{"index": {}}'
           - '{"date": "2020-03-09", "v": 4}'
 
+  - do:
+      indices.forcemerge:
+        index: test_profile
+        max_num_segments: 1
+
   - do:
       search:
         index: test_profile

rest-api-spec/src/main/resources/rest-api-spec/test/search.aggregation/40_range.yml

@@ -544,6 +544,7 @@ setup:
         body:
           settings:
             number_of_replicas: 0
+            number_of_shards: 1
             refresh_interval: -1
           mappings:
             properties:
@@ -567,6 +568,11 @@ setup:
           - '{"index": {}}'
           - '{"double" : 50}'
 
+  - do:
+      indices.forcemerge:
+        index: test_profile
+        max_num_segments: 1
+
   - do:
       search:
         index: test_profile