Making server_id default value match MySQL

Author: fulghum

enginetest/queries/variable_queries.go

@@ -111,7 +111,7 @@ var VariableQueries = []ScriptTest{
 		Assertions: []ScriptTestAssertion{
 			{
 				Query:    "select @@server_id;",
-				Expected: []sql.Row{{uint32(0)}},
+				Expected: []sql.Row{{uint32(1)}},
 			},
 			{
 				Query:    "set @@server_id=123;",

sql/variables/system_variables.go

@@ -2132,7 +2132,7 @@ var systemVars = map[string]sql.SystemVariable{
 		Dynamic:           true,
 		SetVarHintApplies: false,
 		Type:              types.Uint32,
-		Default:           uint32(0),
+		Default:           uint32(1),
 	},
 	"server_uuid": &sql.MysqlSystemVariable{
 		Name:  "server_uuid",