Move dist-x86_64-linux CI job to GitHub temporarily

To make it easier to migrate off the `rust-lang-ci/rust` repository.

(cherry picked from commit 7d32303)

Author: Kobzol

src/ci/github-actions/jobs.yml

@@ -221,7 +221,7 @@ auto:
   - name: dist-x86_64-linux
     env:
       CODEGEN_BACKENDS: llvm,cranelift
-    <<: *job-linux-36c-codebuild
+    <<: *job-linux-16c
 
   - name: dist-x86_64-linux-alt
     env: