Remove _primary and _replica execution preferences (#3884)

Relates: elastic/elasticsearch#26791

Author: russcam

src/Nest/Document/Single/Get/GetRequest.cs

@@ -12,8 +12,6 @@ public partial class GetRequest<TDocument> where TDocument : class { }
 
 	public partial class GetDescriptor<TDocument> where TDocument : class
 	{
-		public GetDescriptor<TDocument> ExecuteOnPrimary() => Preference("_primary");
-
 		public GetDescriptor<TDocument> ExecuteOnLocalShard() => Preference("_local");
 	}
 }

src/Nest/Document/Single/Source/SourceRequest.cs

@@ -14,8 +14,6 @@ public partial class SourceRequest<TDocument> where TDocument : class { }
 
 	public partial class SourceDescriptor<TDocument> where TDocument : class
 	{
-		public SourceDescriptor<TDocument> ExecuteOnPrimary() => Preference("_primary");
-
 		public SourceDescriptor<TDocument> ExecuteOnLocalShard() => Preference("_local");
 	}
 }

src/Nest/Search/Search/SearchRequest.cs

@@ -96,7 +96,7 @@ public partial class SearchRequest
 
 		[JsonFormatter(typeof(IndicesBoostFormatter))]
 		public IDictionary<IndexName, double> IndicesBoost { get; set; }
-		
+
 		public double? MinScore { get; set; }
 		public QueryContainer PostFilter { get; set; }
 		public bool? Profile { get; set; }
@@ -243,29 +243,6 @@ public SearchDescriptor<TInferDocument> Source(Func<SourceFilterDescriptor<TInfe
 		/// </summary>
 		public SearchDescriptor<TInferDocument> TerminateAfter(long? terminateAfter) => Assign(terminateAfter, (a, v) => a.TerminateAfter = v);
 
-		/// <summary>
-		/// <para>
-		/// Controls a preference of which shard replicas to execute the search request on.
-		/// By default, the operation is randomized between the each shard replicas.
-		/// </para>
-		/// <para>
-		/// The operation will go and be executed only on the primary shards.
-		/// </para>
-		/// </summary>
-		public SearchDescriptor<TInferDocument> ExecuteOnPrimary() => Preference("_primary");
-
-		/// <summary>
-		/// <para>
-		/// Controls a preference of which shard replicas to execute the search request on.
-		/// By default, the operation is randomized between the each shard replicas.
-		/// </para>
-		/// <para>
-		/// The operation will go and be executed on the primary shard, and if not available (failover),
-		/// will execute on other shards.
-		/// </para>
-		/// </summary>
-		public SearchDescriptor<TInferDocument> ExecuteOnPrimaryFirst() => Preference("_primary_first");
-
 		/// <summary>
 		/// <para>
 		/// Controls a preference of which shard replicas to execute the search request on.