When a stale schema-cookie is seen, expire only the one statement that

encountered the bad cookie, not every statement on the database 
connection.  Ticket [b72787b1a7cea1f]

FossilOrigin-Name: 1bca0a7e198391202fd2bc1650c0a62028a9aaa5

src/vdbe.c

@@ -2920,7 +2920,7 @@ case OP_VerifyCookie: {
       sqlite3ResetInternalSchema(db, pOp->p1);
     }
 
-    sqlite3ExpirePreparedStatements(db);
+    p->expired = 1;
     rc = SQLITE_SCHEMA;
   }
   break;