github: Update pull request template for clarity

Removed outdated sections and streamlined the pull request template.

.github/PULL_REQUEST_TEMPLATE.md

@@ -1,22 +1,9 @@
 <!--
 
-Thank you for your contribution!
-
-Get early feedback through
-- Dronecode Discord: https://discord.gg/dronecode
-- PX4 Discuss: http://discuss.px4.io/
-- opening a draft pr and sharing the link
-
--->
-
 ### Solved Problem
-When ... I found that ...
-
 Fixes #{Github issue ID}
 
 ### Solution
-- Add ... for ...
-- Refactor ...
 
 ### Changelog Entry
 For release notes:
@@ -27,11 +14,10 @@ Documentation: Need to clarify page ... / done, read docs.px4.io/...
 ```
 
 ### Alternatives
-We could also ...
 
 ### Test coverage
-- Unit/integration test: ...
-- Simulation/hardware testing logs: https://review.px4.io/
 
 ### Context
 Related links, screenshot before/after, video
+
+-->