Disable riscv64-gnu from pr/auto tests

Author: Hoverbear

src/ci/docker/host-x86_64/riscv64gc-gnu/Dockerfile renamed to src/ci/docker/host-x86_64/disabled/riscv64gc-gnu/Dockerfile

@@ -84,9 +84,6 @@ pr:
     <<: *job-linux-16c
   - image: x86_64-gnu-tools
     <<: *job-linux-16c
-  # TODO: This is temporary and for testing https://github.com/rust-lang/rust/pull/125669
-  - image: riscv64gc-gnu
-    <<: *job-linux-4c
 
 # Jobs that run when you perform a try build (@bors try)
 # These jobs automatically inherit envs.try, to avoid repeating
@@ -114,9 +111,6 @@ auto:
   - image: armhf-gnu
     <<: *job-linux-4c
 
-  - image: riscv64gc-gnu
-    <<: *job-linux-4c
-
   - image: dist-aarch64-linux
     env:
       CODEGEN_BACKENDS: llvm,cranelift