Fix warning on boost docs and warning message on non-implementing fieldmappers

docs/reference/mapping/params/boost.asciidoc

@@ -21,6 +21,7 @@ PUT my-index-000001
   }
 }
 --------------------------------------------------
+// TEST[warning:Parameter [boost] on field [title] is deprecated and will be removed in 8.0]
 
 <1> Matches on the `title` field will have twice the weight as those on the
     `content` field, which has the default `boost` of `1.0`.

server/src/main/java/org/elasticsearch/index/mapper/ParametrizedFieldMapper.java

@@ -591,7 +591,7 @@ public abstract class ParametrizedFieldMapper extends FieldMapper {
         // made no sense; if we've got here, that means that they're not declared on a current mapper,
         // and so we emit a deprecation warning rather than failing a previously working mapping.
         private static final Set<String> DEPRECATED_PARAMS
-            = new HashSet<>(Arrays.asList("store", "meta", "index", "doc_values", "boost", "index_options", "similarity"));
+            = new HashSet<>(Arrays.asList("store", "meta", "index", "doc_values", "index_options", "similarity"));
 
         private static boolean isDeprecatedParameter(String propName, Version indexCreatedVersion) {
             return DEPRECATED_PARAMS.contains(propName);