Remove duplicate template (#2239)

.github/ISSUE_TEMPLATE/03_issue_for_leads.yml

@@ -1,37 +0,0 @@
-# Part of the Carbon Language project, under the Apache License v2.0 with LLVM
-# Exceptions. See /LICENSE for license information.
-# SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
-
-name: Issue for leads
-description: >
-  Ask the leads for feedback on an important issue, such as a language design
-  choice.
-labels: [issue for leads]
-body:
-  - type: markdown
-    attributes:
-      value: >
-        **Attention:** If this is a _question_, please use either [GitHub
-        Discussions](https://github.com/carbon-language/carbon-lang/discussions)
-        or [Discord](https://discord.gg/ZjVdShJDAs).
-  - type: textarea
-    id: summary
-    attributes:
-      label: >
-        Summary of issue:
-      description: >
-        Provide a short, one-paragraph summary of the issue.
-  - type: textarea
-    id: detail
-    attributes:
-      label: >
-        Details:
-      description: >
-        Provide detailed information about the issue. For example, on a language
-        design choice, it can help to provide various options with a summary of
-        trade-offs.
-  - type: textarea
-    id: extras
-    attributes:
-      label: >
-        Any other information that you want to share?