Change test-32bit arm32v7 runner to ubuntu-22.04-arm

From ubuntu-24.04-arm, which seems to be having some problems
there too, as discussed in #1828.

This can be viewed as a follow-up on #1802, which made the
analogous change for the non-containerized test job only.

.github/workflows/ci.yml

@@ -209,7 +209,7 @@ jobs:
             toolchain: stable-i686-unknown-linux-gnu
           - container-arch: arm32v7
             runner-arch: arm64
-            runner-os: ubuntu-24.04-arm
+            runner-os: ubuntu-22.04-arm
             toolchain: stable-armv7-unknown-linux-gnueabihf
 
     runs-on: ${{ matrix.runner-os }}