S3Client instantiation extremely slow

### Describe the bug

One of our users has [reported](https://github.com/apache/arrow/issues/40279) that creating a S3Client instance can take up to 1 millisecond. According to profiler statistics, most of the time is spent in `Aws::Crt::Endpoints::RuleEngine` (see linked issue).

### Expected Behavior

I would expect a `S3Client` to be reasonably fast to instantiate (less than a microsecond).

### Current Behavior

See description and profile graph excerpt in linked issue.

### Reproduction Steps

Using PyArrow:
```python
>>> from pyarrow.fs import S3FileSystem
>>> %timeit s = S3FileSystem()
1.29 ms ± 1.27 µs per loop (mean ± std. dev. of 7 runs, 1,000 loops each)
>>> %timeit s = S3FileSystem(anonymous=True)
1.29 ms ± 5.52 µs per loop (mean ± std. dev. of 7 runs, 1,000 loops each)
>>> %timeit s = S3FileSystem(anonymous=True, region='eu-west-1')
1.29 ms ± 4.86 µs per loop (mean ± std. dev. of 7 runs, 1,000 loops each)
```

### Possible Solution

_No response_

### Additional Information/Context

_No response_

### AWS CPP SDK version used

1.11.267

### Compiler and Version used

gcc 12.3.0

### Operating System and version

Ubuntu 22.04