Remove Intel mac CircleCI configuration (#1409)

Also switch bazel-mac to the arm64 config.
The CircleCI Intel mac config will be turned down soon.

scripts/get_release_info.py

@@ -0,0 +1,25 @@
+#!/usr/bin/env python3
+
+import json
+import os
+import sys
+
+def get_latest(tagfile):
+    with open(tagfile) as f:
+        versions = json.load(f)
+        print(versions['aliases']['latest'])
+    return 0
+
+
+def get_hash(tagfile, version):
+    with open(tagfile) as f:
+        versions = json.load(f)
+        print(versions['releases'][version])
+    return 0
+
+
+if __name__ == '__main__':
+    if sys.argv[2] == 'latest':
+        sys.exit(get_latest(sys.argv[1]))
+    if sys.argv[2] == 'hash':
+        sys.exit(get_hash(sys.argv[1], sys.argv[3]))