Feature Not Supported: ALTER TABLE COALESCE PARTITION Not Supported

# Issue: ALTER TABLE COALESCE PARTITION Not Supported

## Description

MatrixOne does not support coalescing partitions using `ALTER TABLE COALESCE PARTITION`. This is a standard MySQL feature for reducing the number of partitions in HASH or KEY partitioned tables.

## Error Statement

```sql
ALTER TABLE test_partition_key COALESCE PARTITION 1;
```

## Error Message

```
ERROR 1064 (HY000) at line 1: SQL parser error: You have an error in your SQL syntax; check the manual that corresponds to your MatrixOne server version for the right syntax to use. syntax error at line 1 column 39 near " COALESCE PARTITION 1"
```

## Expected Behavior

The statement should reduce the number of partitions in the KEY partitioned table by 1, merging the last partition with another partition.

## Actual Behavior

MatrixOne reports a syntax error, indicating that the `COALESCE PARTITION` syntax is not recognized by the parser.

## Impact

- Users cannot reduce the number of partitions in HASH/KEY partitioned tables
- Tables must be recreated to change partition count
- This limits partition management capabilities
- Migration from MySQL may require schema redesign

## Test Case

**Case ID**: 614
**Test File**: `test_batch_62_partition.sql`
**Test Type**: Partition - COALESCE PARTITION operation

## Related Information

- MatrixOne supports creating HASH and KEY partitioned tables
- Other partition management operations (ADD, TRUNCATE, REORGANIZE) are also not supported
- This is part of comprehensive partition functionality testing