Close Interop 2025's call for proposals (#862)

* Update README.md to close the call for Interop 2025 proposals

* Update README.md

* Delete .github/ISSUE_TEMPLATE/investigation-effort-proposal.yml

* Delete .github/ISSUE_TEMPLATE/focus-area-proposal.yml

2025/README.md

@@ -1,9 +1,11 @@
 # Interop 2025
 
-**Interop 2025 is now open for proposals!** Please submit your focus area and/or investigation area proposals [here](https://github.com/web-platform-tests/interop/issues/new/choose).
-
 Interop 2025 is an effort to increase interoperability across browsers in key technical areas that are of high priority to web developers and end users. More details on the project are available in the [Interop Project README](https://github.com/web-platform-tests/interop/blob/main/README.md).
 
+## Proposals
+
+Thank you to everyone who submitted a [proposal for Interop 2025](https://github.com/orgs/web-platform-tests/projects/5)! Please see the timeline below for the ongoing planning of Interop 2025.
+
 ## Timeline
 
 Interop 2025 will open for proposals on September 17, 2024 and the overall timeline is as below. Please note that the timelines are subject to change.

README.md

@@ -4,7 +4,7 @@ Welcome to the Interop Project, an ongoing effort to make the web more interoper
 
 Please see the [Interop 2024 Dashboard](https://wpt.fyi/interop-2024) and [Interop 2024 README](./2024/README.md) for the current iteration of the project!
 
-__Interop 2025 is open for proposals from Sep 17th, 2024 to Oct 9th, 2024.__ The Interop Team will evaluate and select proposals in the following months. Interop 2025 and the set of accepted proposals will be announced in the first half of Feb 2025. Please see the [Interop 2025 README](./2025/README.md) for details.
+Please see the [Interop 2025 README](./2025/README.md) for the ongoing planning of Interop 2025, which will be announced in early 2025.
 
 ## The Purpose of the Interop Project