remove default pipelines from exercise config

Exercise-Configuration.md

@@ -159,12 +159,6 @@ Mandatory items are bold, optional italic, description of items follows:
 * **environments** - list of environments identifiers which belong to exercise
 * **tests** - map of tests indexed by test unique identifier
     * **${test identification}** - test unique identifier
-        * **pipelines** - list of default pipelines for this test
-            * **name** - identifier of pipeline from database entity
-            * **variables** - list of variables
-                * **name** - unique identifier of the variable
-                * **type** - one of the supported variable types
-                * **value** - either single scalar value or array is variable is of array type
         * **environments** - map of environments which redefines default pipelines from this test
             * **${environment identification}** - unique environment identifier from database
                 * **pipelines** - list of redefined pipelines, if this list is empty, then list of pipelines is replaced by defaults