[fix](cloud compaction) horizontal compaction coredump due to tablet shard_ptr not initialized (#58751)

```
#0  0x000055f11470ff29 in std::__shared_ptr<doris::TabletMeta, (__gnu_cxx::_Lock_policy)2>::get (this=0x148) at /home/work/env/ldb_toolchain_master/bin/../lib/gcc/x86_64-pc-linux-gnu/15/include/g++-v15/bits/shared_ptr_base.h:1673

#1  std::__shared_ptr_access<doris::TabletMeta, (__gnu_cxx::_Lock_policy)2, false, false>::_M_get (this=0x148) at /home/work/env/ldb_toolchain_master/bin/../lib/gcc/x86_64-pc-linux-gnu/15/include/g++-v15/bits/shared_ptr_base.h:1370

#2  std::__shared_ptr_access<doris::TabletMeta, (__gnu_cxx::_Lock_policy)2, false, false>::operator-> (this=0x148) at /home/work/env/ldb_toolchain_master/bin/../lib/gcc/x86_64-pc-linux-gnu/15/include/g++-v15/bits/shared_ptr_base.h:1364

#3  doris::BaseTablet::tablet_id (this=0x0) at /home/work/doris/be/src/olap/base_tablet.h:73

#4  doris::segment_v2::SegmentWriter::finalize (this=0x7fa160bde000, segment_file_size=0x7fa564dcc668, index_size=0x7fa564dcc5b8) at /home/work/doris/be/src/olap/rowset/segment_v2/segment_writer.cpp:1044

#5  0x000055f11442578c in doris::SegmentFlusher::_flush_segment_writer (this=0x7fa160b8a420, writer=..., flush_size=flush_size@entry=0x0) at /home/work/doris/be/src/olap/rowset/segment_creator.cpp:304

#6  0x000055f114426c4e in doris::SegmentFlusher::Writer::flush (this=<optimized out>) at /home/work/doris/be/src/olap/rowset/segment_creator.cpp:376

#7  doris::SegmentCreator::flush (this=0x7fa160b8a418) at /home/work/doris/be/src/olap/rowset/segment_creator.cpp:422

#8  0x000055f1143d4785 in doris::BaseBetaRowsetWriter::flush (this=<optimized out>) at /home/work/doris/be/src/olap/rowset/beta_rowset_writer.cpp:723

#9  0x000055f11436bf47 in doris::Merger::vmerge_rowsets (tablet=..., reader_type=<optimized out>, cur_tablet_schema=..., src_rowset_readers=..., dst_rowset_writer=0x7fa160b8a000, stats_output=0x7fa1df108298) at /home/work/doris/be/src/olap/merger.cpp:159

#10 0x000055f114345595 in doris::Compaction::merge_input_rowsets (this=this@entry=0x7fa1df108210) at /home/work/doris/be/src/olap/compaction.cpp:220

#11 0x000055f1143550d2 in doris::CloudCompactionMixin::execute_compact_impl (this=this@entry=0x7fa1df108210, permits=permits@entry=6) at /home/work/doris/be/src/olap/compaction.cpp:1491

#12 0x000055f114342bc1 in doris::CloudCompactionMixin::execute_compact (this=0x7fa1df108210) at /home/work/doris/be/src/olap/compaction.cpp:1620

#13 0x000055f11a22c6d8 in doris::CloudCumulativeCompaction::execute_compact (this=0x7fa1df108210) at /home/work/doris/be/src/cloud/cloud_cumulative_compaction.cpp:203
```

Author: HonestManXin

be/src/olap/compaction.cpp

@@ -1506,6 +1506,7 @@ Status CloudCompactionMixin::construct_output_rowset_writer(RowsetWriterContext&
     ctx.write_file_cache = should_cache_compaction_output();
     ctx.file_cache_ttl_sec = _tablet->ttl_seconds();
     ctx.approximate_bytes_to_write = _input_rowsets_total_size;
+    ctx.tablet = _tablet;
 
     _output_rs_writer = DORIS_TRY(_tablet->create_rowset_writer(ctx, _is_vertical));
     RETURN_IF_ERROR(