TreeUnpickler: avoid forcing annotations early

This sometimes lead to cycles when compiling the 2.13 stdlib and shouldn't
be necessary anymore (all the tests pass).

Author: smarter

compiler/src/dotty/tools/dotc/core/tasty/TreeUnpickler.scala

@@ -839,13 +839,6 @@ class TreeUnpickler(reader: TastyReader,
             DefDef(Nil, Nil, tpt)
           }
       }
-      val mods =
-        if (sym.annotations.isEmpty) untpd.EmptyModifiers
-        else untpd.Modifiers(annotations = sym.annotations.map(_.tree))
-      tree.withMods(mods)
-        // record annotations in tree so that tree positions can be filled in.
-        // Note: Once the inline PR with its changes to positions is in, this should be
-        // no longer necessary.
       goto(end)
       setSpan(start, tree)
       if (!sym.isType) { // Only terms might have leaky aliases, see the documentation of `checkNoPrivateLeaks`