False positive: Ruby: Kernel Open when File existence guard is present

**Description of the false positive**

When `IO.read` is guarded by a check like `File.exists?`, isn't that a valid guard against injecting the `|` character into `Kernel.open`? I don't imagine that many systems out there have files lying around named `|.txt`.

**Code samples or links to source code**

https://github.com/github/codeql/blob/81593ece5aa7701ec0b103932f84ff65ae506e0b/ruby/ql/lib/codeql/ruby/security/KernelOpenQuery.qll#L83C1-L87

**URL to the alert on GitHub code scanning (optional)**
- https://github.com/Chainguard-Wolfi-Bites-Back/opensearch-project__logstash-output-opensearch/security/code-scanning/2
- https://github.com/opensearch-project/logstash-output-opensearch/blob/4221dffef4c1d9fd5ded5ae726ef2874fdd9ba5b/lib/logstash/outputs/opensearch/template_manager.rb#L55-L59

閱讀 ruby/ql/lib/codeql/ruby/security/KernelOpenQuery.qll 第 83-87 行附近的內容，並檢查 template_manager.rb 第 55-59 行附近連結的 Ruby 範例。判斷 File.exists? 守衛是否應抑制此 Kernel.open 警示，然後驗證查詢對回報模式及相關案例的行為。

由索引模型根據 Issue 內容生成。