Auto merge of rust-lang#127023 - Kobzol:ci-rfl-rename, r=<try>

CI: rename Rust for Linux CI job

The `rfl` name was not very [descriptive](https://rust-lang.zulipchat.com/#narrow/stream/242791-t-infra/topic/Testing.20Rust.20for.20Linux.20in.20our.20CI/near/447408854).

try-job: rust-for-linux

Author: bors

src/ci/docker/host-x86_64/rfl/Dockerfile renamed to src/ci/docker/host-x86_64/rust-for-linux/Dockerfile

@@ -468,5 +468,5 @@ auto:
 
   # Tests integration with Rust for Linux.
   # Builds stage 1 compiler and tries to compile a few RfL examples with it.
-  - image: rfl
+  - image: rust-for-linux
     <<: *job-linux-8c