[Pick](Variant) pick 2 prs about bugfix of variant (#33011)

* [Fix](Variant) forbit table with variant type doing segment compaction temporarily

TODO fix this corretly in later works

* [Bug](Variant) use lower case name for variant's root, since backend treat parent column as lower case

This PR address the problem as blow:
```
errCode = 2, detailMessage = (172.16.56.137)[CANCELLED]failed to initialize storage reader. tablet=17136, res=[INTERNAL_ERROR]Not found field_name, field_name:Tags.tag_key1, schema:[Thread(8), Tags(9), Source(5), tags.tag_key1(-1), Title(6), Level(3), Time(2), CreateDate(1), Message(7), IP(4), AppId(0)]

```

be/src/olap/rowset/beta_rowset_writer.cpp

@@ -416,7 +416,8 @@ Status BetaRowsetWriter::_segcompaction_if_necessary() {
     // otherwise _segcompacting_cond will never get notified
     if (!config::enable_segcompaction || !_context.enable_segcompaction ||
         !_context.tablet_schema->cluster_key_idxes().empty() ||
-        !_check_and_set_is_doing_segcompaction()) {
+        !_check_and_set_is_doing_segcompaction() ||
+        _context.tablet_schema->num_variant_columns() > 0) {
         return status;
     }
     if (_segcompaction_status.load() != OK) {

fe/fe-core/src/main/java/org/apache/doris/nereids/glue/translator/PlanTranslatorContext.java

@@ -289,7 +289,7 @@ public SlotDescriptor createSlotDesc(TupleDescriptor tupleDesc, SlotReference sl
             slotRef = new SlotRef(slotDescriptor);
             if (slotReference.hasSubColPath()) {
                 slotDescriptor.setSubColLables(slotReference.getSubColPath());
-                slotDescriptor.setMaterializedColumnName(slotRef.getColumnName()
+                slotDescriptor.setMaterializedColumnName(slotRef.getColumnName().toLowerCase()
                             + "." + String.join(".", slotReference.getSubColPath()));
             }
         }

regression-test/data/variant_p0/column_name.out

@@ -20,3 +20,15 @@
 \N	\N
 UPPER CASE	lower case
 
+-- !sql --
+1	{"tag_key1":123456}
+
+-- !sql --
+1	{"tag_key1":123456}
+
+-- !sql --
+1	{"tag_key1":123456}
+
+-- !sql --
+1	{"tag_key1":123456}
+

regression-test/suites/variant_p0/column_name.groovy

@@ -43,5 +43,11 @@ suite("regression_test_variant_column_name", "variant_type"){
     // sql """insert into ${table_name} values (6, '{"\\n123": "t123", "\\\"123": "123"}')"""
     sql """insert into ${table_name} values (7, '{"AA": "UPPER CASE", "aa": "lower case"}')"""
     qt_sql """select cast(v["AA"] as string), cast(v["aa"] as string) from ${table_name} order by k"""
-
+
+    sql "alter table var_column_name rename column v Tags;  "
+    sql """insert into var_column_name values (1, '{"tag_key1" : 123456}')"""
+    qt_sql "select * from var_column_name where tags['tag_key1'] is not null and cast(Tags['tag_key1' ] as text) = '123456' order by k desc limit 1;"    
+    qt_sql "select * from var_column_name where tags['tag_key1'] is not null and cast(tags['tag_key1' ] as text) = '123456' order by k desc limit 1;"    
+    qt_sql "select * from var_column_name where Tags['tag_key1'] is not null and cast(tags['tag_key1' ] as text) = '123456' order by k desc limit 1;"    
+    qt_sql "select * from var_column_name where Tags['tag_key1'] is not null and cast(Tags['tag_key1' ] as text) = '123456' order by k desc limit 1;"    
 }