Handle total hits equal to track_total_hits (#37907)

This change ensures that a total hits equal to the value set for
track_total_hits is not considered as a lower bound.

rest-api-spec/src/main/resources/rest-api-spec/test/search/220_total_hits_object.yml

@@ -56,7 +56,7 @@ setup:
 ---
 "hits.total as an object":
   - skip:
-      version: " - 6.99.99"
+      version: " - 7.0.99"
       reason: hits.total is rendered as an object in 7.0.0
 
   - do:
@@ -106,7 +106,7 @@ setup:
 
   - do:
       search:
-        size: 3
+        size: 0
         track_total_hits: 4
         body:
           query:
@@ -116,6 +116,18 @@ setup:
   - match: {hits.total.value: 4}
   - match: {hits.total.relation: gte}
 
+  - do:
+      search:
+        size: 0
+        track_total_hits: 5
+        body:
+          query:
+            match:
+              foo: bar
+
+  - match: {hits.total.value: 5}
+  - match: {hits.total.relation: eq}
+
   - do:
       catch: /\[rest_total_hits_as_int\] cannot be used if the tracking of total hits is not accurate, got 100/
       search:

server/src/main/java/org/elasticsearch/action/search/SearchPhaseController.java

@@ -754,7 +754,7 @@ public final class SearchPhaseController {
                 assert totalHitsRelation == Relation.EQUAL_TO;
                 return new TotalHits(totalHits, totalHitsRelation);
             } else {
-                if (totalHits < trackTotalHitsUpTo) {
+                if (totalHits <= trackTotalHitsUpTo) {
                     return new TotalHits(totalHits, totalHitsRelation);
                 } else {
                     /*