## What changes were proposed in this pull request?
Currently, `github_jira_sync.py` assumes that there is `Link` always. However, it will fail when the number of the open PR is less than 100 (the default paging number). It will not happen in Apache Spark, but we had better fix that because it happens during review process for `github_jira_sync.py` script.
```
Traceback (most recent call last):
File "dev/github_jira_sync.py", line 139, in <module>
jira_prs = get_jira_prs()
File "dev/github_jira_sync.py", line 83, in get_jira_prs
link_header = filter(lambda k: k.startswith("Link"), page.info().headers)[0]
IndexError: list index out of range
```
## How was this patch tested?
Manually check with another repo which has small number of open PRs (< 100).
```
$ export JIRA_PASSWORD=...
$ export GITHUB_API_BASE='https://api.github.com/repos/your-id/spark'
$ dev/github_jira_sync.py
```
Closes#24874 from dongjoon-hyun/SPARK-28053.
Authored-by: Dongjoon Hyun <dhyun@apple.com>
Signed-off-by: HyukjinKwon <gurwls223@apache.org>
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