[Fix](DDL) Make autoBucket flag modifiable and add testcases for ALTER TABLE BUCKETS (#60651)

Author: zclllyybb

fe/fe-core/src/main/java/org/apache/doris/catalog/DistributionInfo.java

@@ -64,19 +64,21 @@ public DistributionInfoType getType() {
     }
 
     public int getBucketNum() {
-        // should override in sub class
-        throw new NotImplementedException("not implemented");
+        return bucketNum;
     }
 
     public void setBucketNum(int bucketNum) {
-        // should override in sub class
-        throw new NotImplementedException("not implemented");
+        this.bucketNum = bucketNum;
     }
 
     public void markAutoBucket() {
         autoBucket = true;
     }
 
+    public void setAutoBucket(boolean autoBucket) {
+        this.autoBucket = autoBucket;
+    }
+
     public DistributionDesc toDistributionDesc() {
         throw new NotImplementedException("toDistributionDesc not implemented");
     }

fe/fe-core/src/main/java/org/apache/doris/catalog/Env.java

@@ -6245,6 +6245,8 @@ public void modifyDefaultDistributionBucketNum(Database db, OlapTable olapTable,
                 }
 
                 defaultDistributionInfo.setBucketNum(bucketNum);
+                defaultDistributionInfo.setAutoBucket(distributionInfo.getAutoBucket());
+                olapTable.setIsAutoBucket(distributionInfo.getAutoBucket());
 
                 ModifyTableDefaultDistributionBucketNumOperationLog info
                         = new ModifyTableDefaultDistributionBucketNumOperationLog(db.getId(), olapTable.getId(),
@@ -6270,6 +6272,8 @@ public void replayModifyTableDefaultDistributionBucketNum(ModifyTableDefaultDist
         try {
             DistributionInfo defaultDistributionInfo = olapTable.getDefaultDistributionInfo();
             defaultDistributionInfo.setBucketNum(bucketNum);
+            defaultDistributionInfo.setAutoBucket(info.getAutoBucket());
+            olapTable.setIsAutoBucket(info.getAutoBucket());
         } finally {
             olapTable.writeUnlock();
         }

fe/fe-core/src/main/java/org/apache/doris/catalog/HashDistributionInfo.java

@@ -54,16 +54,6 @@ public List<Column> getDistributionColumns() {
         return distributionColumns;
     }
 
-    @Override
-    public int getBucketNum() {
-        return bucketNum;
-    }
-
-    @Override
-    public void setBucketNum(int bucketNum) {
-        this.bucketNum = bucketNum;
-    }
-
     public boolean sameDistributionColumns(HashDistributionInfo other) {
         if (distributionColumns.size() != other.distributionColumns.size()) {
             return false;

fe/fe-core/src/main/java/org/apache/doris/catalog/RandomDistributionInfo.java

@@ -44,11 +44,6 @@ public DistributionDesc toDistributionDesc() {
         return distributionDesc;
     }
 
-    @Override
-    public int getBucketNum() {
-        return bucketNum;
-    }
-
     @Override
     public String getColumnsName() {
         return "";