ci: Move "i686: Linux (Debian stable)" from Cirrus to GiHub Actions

.cirrus.yml

@@ -64,24 +64,6 @@ linux_container_snippet: &LINUX_CONTAINER
     # More than enough for our scripts.
     memory: 2G
 
-task:
-  name: "i686: Linux (Debian stable)"
-  << : *LINUX_CONTAINER
-  env:
-    HOST: i686-linux-gnu
-    ECDH: yes
-    RECOVERY: yes
-    SCHNORRSIG: yes
-    ELLSWIFT: yes
-  matrix:
-    - env:
-        CC: i686-linux-gnu-gcc
-    - env:
-        CC: clang --target=i686-pc-linux-gnu -isystem /usr/i686-linux-gnu/include
-  test_script:
-    - ./ci/ci.sh
-  << : *CAT_LOGS
-
 task:
   name: "s390x (big-endian): Linux (Debian stable, QEMU)"
   << : *LINUX_CONTAINER