Adjust bwc version for exists query tests

Author: colings86

rest-api-spec/src/main/resources/rest-api-spec/test/search/160_exists_query.yml

@@ -584,7 +584,7 @@ setup:
 ---
 "Test exists query on _uid field":
   - skip:
-      version: " - 6.1.0"
+      version: " - 6.0.99"
       reason: exists on _uid not supported prior to 6.1.0
   - do:
       search:
@@ -599,7 +599,7 @@ setup:
 ---
 "Test exists query on _index field":
   - skip:
-      version: " - 6.1.0"
+      version: " - 6.0.99"
       reason: exists on _index not supported prior to 6.1.0
   - do:
       search:
@@ -614,7 +614,7 @@ setup:
 ---
 "Test exists query on _type field":
   - skip:
-      version: " - 6.1.0"
+      version: " - 6.0.99"
       reason: exists on _type not supported prior to 6.1.0
   - do:
       search:
@@ -653,7 +653,7 @@ setup:
 ---
 "Test exists query on _source field":
   - skip:
-      version: " - 6.1.0"
+      version: " - 6.0.99"
       reason: exists on _source not supported prior to 6.1.0
   - do:
       catch: /query_shard_exception/