…8240)

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### What changes were proposed in this pull request?

Fixed the `DorisUtils.extractBucketNum()` method to properly handle
`BUCKETS AUTO` parsing for `DISTRIBUTED BY RANDOM` statements. The
method was incorrectly calling `matcher.find(5)` which advances the
matcher position, causing the bucket value extraction to fail and
resulting in a `NumberFormatException` when parsing null values.

**Changes:**
- Changed `if (matcher.find(5))` to `if (matcher.group(5) != null)` in
`DorisUtils.extractBucketNum()`
- Added test case for `DISTRIBUTED BY RANDOM BUCKETS AUTO` in
`TestDorisUtils.testDistributedInfoPattern()`

### Why are the changes needed?

This fixes a critical bug where Doris table operations fail when
encountering `DISTRIBUTED BY RANDOM BUCKETS AUTO` syntax. The root cause
was that `matcher.find(5)` advances the matcher position after the
initial match, and since there are no subsequent matches, it returns
`false` and never reaches the bucket value extraction logic. This leaves
`bucketValue` as null, causing `Integer.valueOf(bucketValue)` to throw
`NumberFormatException: Cannot parse null string`.

The bug affects users trying to load tables with auto bucket
distribution using random strategy, which is a valid Doris SQL syntax.

  Fix: #8218 

### Does this PR introduce _any_ user-facing change?

No user-facing API changes. This is a bug fix that enables proper
parsing of existing Doris SQL syntax that was previously failing. Users
can now successfully work with tables using `DISTRIBUTED BY RANDOM
BUCKETS AUTO` without encountering parsing errors.

### How was this patch tested?


1. **Existing tests**: Verified all existing Doris utility tests
continue to pass, ensuring no regression
2. **New test case**: Added
`TestDorisUtils.testDistributedInfoPattern()` test case specifically for
`DISTRIBUTED BY RANDOM BUCKETS AUTO` to prevent future regressions
3. **Manual verification**: Created and ran a standalone test to
reproduce the original bug and verify the fix resolves the
`NumberFormatException`
4. **Code formatting**: Applied Spotless formatting to ensure code style
compliance

**Test command:**
```
./gradlew :catalogs:catalog-jdbc-doris:test --tests="*TestDorisUtils*"
```

All tests pass successfully with the fix applied.