Rules.xtext: remove unused imports (#5420)

bundles/org.openhab.core.model.rule/src/org/openhab/core/model/rule/Rules.xtext

@@ -1,9 +1,5 @@
 grammar org.openhab.core.model.rule.Rules with org.openhab.core.model.script.Script
 
-import "http://www.eclipse.org/xtext/xbase/Xbase" as xbase
-import "http://www.eclipse.org/xtext/common/JavaVMTypes" as types
-import "http://www.eclipse.org/emf/2002/Ecore" as ecore
-
 generate rules "https://openhab.org/model/Rules"
 
 RuleModel:
@@ -11,10 +7,6 @@ RuleModel:
 	(variables+=VariableDeclaration)*
 	(rules += Rule)*;
 
-//Import:
-//	'import' importedNamespace=QualifiedNameWithWildcard
-//;
-
 VariableDeclaration:
 	(writeable?='var'|'val') (=>(type=JvmTypeReference name=ValidID) | name=ValidID) ('=' right=XExpression)?
 ;