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

This PR automatically iterates to the next branch to be merged instead of using the latest all the time

### Why are the changes needed?

anti-misoperation

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

no

### How was this patch tested?

### Was this patch authored or co-authored using generative AI tooling?

Locally tested

```python
>>> def get_json(url):
...     try:
...         request = Request(url)
...         if GITHUB_OAUTH_KEY:
...             request.add_header("Authorization", "token %s" % GITHUB_OAUTH_KEY)
...         return json.load(urlopen(request))
...     except HTTPError as e:
...         if "X-RateLimit-Remaining" in e.headers and e.headers["X-RateLimit-Remaining"] == "0":
...             print(
...                 "Exceeded the GitHub API rate limit; see the instructions in "
...                 + "dev/merge_spark_pr.py to configure an OAuth token for making authenticated "
...                 + "GitHub requests."
...             )
...         else:
...             print("Unable to fetch URL, exiting: %s" % url)
...         sys.exit(-1)
...
>>> branches = get_json("%s/branches" % GITHUB_API_BASE)
>>>
>>> branch_names = list(filter(lambda x: x.startswith("branch-"), [x["name"] for x in branches]))
>>> branch_names = sorted(branch_names, reverse=True)
>>> branch_iter = iter(branch_names)
>>> print(next(branch_iter, branch_names[0]))
branch-3.5
>>> print(next(branch_iter, branch_names[0]))
branch-3.4
>>> print(next(branch_iter, branch_names[0]))
branch-3.3
>>> print(next(branch_iter, branch_names[0]))
branch-3.2
>>> print(next(branch_iter, branch_names[0]))
branch-3.1
>>> print(next(branch_iter, branch_names[0]))
branch-3.0
>>> print(next(branch_iter, branch_names[0]))
branch-2.4
>>> print(next(branch_iter, branch_names[0]))
branch-2.3
>>> print(next(branch_iter, branch_names[0]))
branch-2.2
>>> print(next(branch_iter, branch_names[0]))
branch-2.1
>>> print(next(branch_iter, branch_names[0]))
branch-2.0
>>> print(next(branch_iter, branch_names[0]))
branch-1.6
>>> print(next(branch_iter, branch_names[0]))
branch-1.5
>>> print(next(branch_iter, branch_names[0]))
branch-1.4
>>> print(next(branch_iter, branch_names[0]))
branch-1.3
>>> print(next(branch_iter, branch_names[0]))
branch-1.2
>>> print(next(branch_iter, branch_names[0]))
branch-1.1
>>> print(next(branch_iter, branch_names[0]))
branch-1.0-jdbc
>>> print(next(branch_iter, branch_names[0]))
branch-1.0
>>> print(next(branch_iter, branch_names[0]))
branch-0.9
>>> print(next(branch_iter, branch_names[0]))
branch-0.8
>>> print(next(branch_iter, branch_names[0]))
branch-0.7
>>> print(next(branch_iter, branch_names[0]))
branch-0.6
>>> print(next(branch_iter, branch_names[0]))
branch-0.5
>>> print(next(branch_iter, branch_names[0]))
branch-3.5
>>> quit()
```

Closes apache#42723 from yaooqinn/SPARK-45008.

Authored-by: Kent Yao <yao@apache.org>
Signed-off-by: Dongjoon Hyun <dhyun@apple.com>