[BugFix] Be crash when doing compaction apply (#14513)

This bug is introduced by #12068. To reduce the memory usage during apply, we don't preload all segments' primary keys and process segment by segment(#12068).

```
 ....
 uint32_t max_rowset_id = *std::max_element(info->inputs.begin(), info->inputs.end());
 Rowset* rowset = _get_rowset(max_rowset_id).get();
 .....
 for (size_t i = 0; i < _compaction_state->pk_cols.size(); i++) {
       // the rowset is not what we should load
       if (st = _compaction_state->load_segments(rowset, i); !st.ok()) {
            manager->index_cache().release(index_entry);
            _compaction_state.reset();
            std::string msg = strings::Substitute("_apply_compaction_commit error: load compaction state failed: $0 $1",
                                                  st.to_string(), debug_string());
            LOG(ERROR) << msg;
            _set_error(msg);
            return;
        }
        .....
    }
```
As the above code shown, we will load one segment for a loop. However, the `rowset` is not the output rowset after compaction but one of the input rowsets, so we may get an unexpected error.

(cherry picked from commit 287f82a)

be/src/storage/tablet_updates.cpp

@@ -1411,7 +1411,15 @@ void TabletUpdates::_apply_compaction_commit(const EditVersionInfo& version_info
         _set_error(msg);
         return;
     }
-    if (!(st = _compaction_state->load(_get_rowset(rowset_id).get())).ok()) {
+    Rowset* output_rowset = _get_rowset(rowset_id).get();
+    if (output_rowset == nullptr) {
+        string msg = strings::Substitute("_apply_compaction_commit rowset not found tablet=$0 rowset=$1",
+                                         _tablet.tablet_id(), rowset_id);
+        LOG(ERROR) << msg;
+        _set_error(msg);
+        return;
+    }
+    if (!(st = _compaction_state->load(output_rowset)).ok()) {
         manager->index_cache().release(index_entry);
         _compaction_state.reset();
         std::string msg = Substitute("_apply_compaction_commit error: load compaction state failed: $0 $1",
@@ -1442,7 +1450,7 @@ void TabletUpdates::_apply_compaction_commit(const EditVersionInfo& version_info
     uint32_t max_src_rssid = max_rowset_id + rowset->num_segments() - 1;
 
     for (size_t i = 0; i < _compaction_state->pk_cols.size(); i++) {
-        if (st = _compaction_state->load_segments(rowset, i); !st.ok()) {
+        if (st = _compaction_state->load_segments(output_rowset, i); !st.ok()) {
             manager->index_cache().release(index_entry);
             _compaction_state.reset();
             std::string msg = Substitute("_apply_compaction_commit error: load compaction state failed: $0 $1",