Don't run CI on intel macOS (#3900)

We are dropping support for intel macOS across the K ecosystem;
supporting these machines slows build times down substantially in some
places, and we don't have any core developers left using them.

Part of: runtimeverification/k#4368

Co-authored-by: Georgy Lukyanov <[email protected]>
Co-authored-by: Jost Berthold <[email protected]>

Author: 3 people

.github/workflows/release.yml

@@ -46,9 +46,6 @@ jobs:
           - runner: ubuntu-22.04
             os: ubuntu-22.04
             nix: x86_64-linux
-          - runner: macos-12
-            os: macos-12
-            nix: x86_64-darwin
           - runner: MacM1
             os: self-macos-12
             nix: aarch64-darwin

.github/workflows/test.yml

@@ -78,9 +78,6 @@ jobs:
           - runner: ubuntu-22.04
             os: ubuntu-22.04
             nix: x86_64-linux
-          - runner: macos-12
-            os: macos-12
-            nix: x86_64-darwin
           - runner: MacM1
             os: self-macos-12
             nix: aarch64-darwin