[C++] HeadBucket called in S3FS breaking IAM scoped prefixes

If you have a bucket `s3://mybucket` which has prefixes which you are allowed to write into via IAM roles, e.g. `s3://mybucket/allowed_dir`, you cannot currently use `S3FileSystem::CreateDir(path, recursive=true)` because a call of HeadBucket.

For e.g.:
```
(base) ray@ryan-test-head-wkzmw:~$ python
Python 3.12.9 | packaged by Anaconda, Inc. | (main, Feb 6 2025, 18:56:27) [GCC 11.2.0] on linux
Type "help", "copyright", "credits" or "license" for more information.
>>> import pyarrow
>>> import pyarrow.fs as fs
>>> s3 = fs.S3FileSystem()
>>> s3.create_dir("test-bucket/pepperr/test", recursive=True)
Traceback (most recent call last):
File "", line 1, in
File "pyarrow/_fs.pyx", line 638, in pyarrow._fs.FileSystem.create_dir
File "pyarrow/error.pxi", line 92, in pyarrow.lib.check_status
OSError: When testing for existence of bucket 'test-bucket': AWS Error ACCESS_DENIED during HeadBucket operation: No response body.
```
In this case, the bucket exists, but the user is not allowed to do the HEAD operation on the root bucket itself. Nonetheless, the user is able to write/do things in this location, so they should not be blocked by this.
```
>>> boto3.client("s3").put_object(Bucket="test-bucket", Key="pepperr/test/probe.txt", Body=b"hello")
{'ResponseMetadata': {'RequestId': 'FXJ3YG658VKQ8725', 'HostId': '37ezZQHJ0KzbBAQEU6uuDYWIIBa9XpNqs/E6neTpT/8XDpTIh7TE6hBXrHJDT+19STrC6QRcUKlp1zqeIMlLfCnvU/lPvtCp', 'HTTPStatusCode': 200, ....}
```

I think the check comes in here on line 3177; if recursive=True, then you hit a code block which checks if the bucket exists:
https://github.com/apache/arrow/blob/ebaaf07adbd302e95e393b5b77d78c1c97ea3b70/cpp/src/arrow/filesystem/s3fs.cc#L3162-L3180
Whereas this needs to actually be more permissive; the S3 call should be issued rather than performing an explicit check for bucket existence, and failure reported up the stack.

### Component(s)

C++