In 3.x and 2.x scores, open part scores by default

Because they were open by default in 3.x and 2.x

Resolves: #23073

Author: cbjeukendrup

src/engraving/rw/read206/read206.cpp

@@ -3478,6 +3478,7 @@ bool Read206::readScoreTag(Score* score, XmlReader& e, ReadContext& ctx)
             ctx.setLastMeasure(nullptr);
             ReadContext exCtx(s);
 
+            s->setIsOpen(true);
             readScoreTag(s, e, exCtx);
 
             ex->setTracksMapping(ctx.tracks());

src/engraving/rw/read302/read302.cpp

@@ -156,6 +156,7 @@ bool Read302::readScoreTag(Score* score, XmlReader& e, ReadContext& ctx)
             Score* curScore = ctx.score();
             ctx.setScore(s);
 
+            s->setIsOpen(true);
             readScoreTag(s, e, ctx);
 
             ctx.setScore(curScore);