chore: remove automatic sql variable extraction

one must explicitly call `extract` using column- plut target-variable-names
in order to extract data from the result into the current `TestContext`.

BREAKING CHANGE: sql queries no longer automatically extract variables

connectors/citrus-sql/src/main/java/org/citrusframework/actions/ExecuteSQLQueryAction.java

@@ -123,12 +123,6 @@ public void doExecute(TestContext context) {
 
             // fill the request test context variables (extract tag)
             fillContextVariables(columnValuesMap, context);
-
-            // legacy: save all columns as variables TODO: remove in major version upgrade
-            for (Entry<String, List<String>> column : columnValuesMap.entrySet()) {
-                List<String> columnValues = column.getValue();
-                context.setVariable(column.getKey().toUpperCase(), columnValues.get(0) == null ? NULL_VALUE : columnValues.get(0));
-            }
         } catch (DataAccessException e) {
             logger.error("Failed to execute SQL statement", e);
             throw new CitrusRuntimeException(e);