Don't force annotation unpickling when testing for SilentIntoAnnot

[odersky]

Don't force completion of annotation unpickling when testing for SilentIntoAnnot

Fixes #23496

[odersky]

I should have seen error in the original commit.

[odersky]

The windows test was failing, presumably because it used a different file order in the compilation than the main test. I verified that the following order gives a cyclic reference error:

scalac annotations_1.scala Query_1.scala ScalaqlSyntax_1.scala package.scala_1.scala

The error under -explain-cylic is:

~/workspace/dotty/tests/pos/i23496> sc annotations_1.scala Query_1.scala ScalaqlSyntax_1.scala package.scala_1.scala -explain-cyclic
-- [E046] Cyclic Error: annotations_1.scala:5:35 -------------------------------
5 |class forbiddenInheritance extends StaticAnnotation
  |                                   ^
  |Cyclic reference involving val <import>
  |
  |The error occurred while trying to compute the signature of import scala.annotation.StaticAnnotation
  |  which required to compute the signature of package object scalaql
  |  which required to compute the base classes of trait ScalaqlSyntax
  |  which required to compute the signature of trait ScalaqlSyntax
  |  which required to compute the base classes of class forbiddenInheritance
  |  which required to compute the signature of class forbiddenInheritance
  |  which required to compute the signature of import scala.annotation.StaticAnnotation
  |
  | Run with both -explain-cyclic and -Ydebug-cyclic to see full stack trace.
  |
  | longer explanation available when compiling with `-explain`
-- Error: ScalaqlSyntax_1.scala:3:0 --------------------------------------------
3 |@scalaql.forbiddenInheritance
  |^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  |class forbiddenInheritance is not a valid Scala annotation: it does not extend `scala.annotation.Annotation`

I thought of creating an issue for this. But then I noted that the project uses a package object inheritance of an inner trait which should be illegal:

import scalaql.syntax.ScalaqlSyntax

package object scalaql extends ScalaqlSyntax

So I guess we should work on making this illegal, instead of trying to fix the consequences to the typing.

The workaround is to not to use an import in forbiddenInheritance. That's the next commit.