delete old deprecations

javascript/ql/src/Declarations/Definitions.qll

@@ -1,13 +1 @@
 import javascript
-
-/**
- * DEPRECATED: Use `SsaDefinition` from `SSA.qll` instead.
- * An identifier appearing in a defining position.
- */
-deprecated class DefiningIdentifier extends Identifier {
-  DefiningIdentifier() {
-    this instanceof VarDecl or
-    exists(Assignment assgn | this = assgn.getLhs()) or
-    exists(UpdateExpr upd | this = upd.getOperand())
-  }
-}