ci(appveyor): give more descriptive names to Mac matrix runs, remove …

…identical, test one against datalad/packages way

Unclear why there were 3 identical!  interestingly some did time out with brew installation of annex, some succeeded.
So I guess it would remain flaky

.appveyor.yml

@@ -80,18 +80,16 @@ environment:
       #INSTALL_GITANNEX: git-annex=8.20201129
       INSTALL_GITANNEX: git-annex
 
-    - ID: MacP310a1
+    - ID: MacP310-default
       APPVEYOR_BUILD_WORKER_IMAGE: macos-monterey
       PY: 3.10
+      # ATM default is brew
       INSTALL_GITANNEX: git-annex
-    - ID: MacP310a2
-      APPVEYOR_BUILD_WORKER_IMAGE: macos-monterey
-      PY: 3.10
-      INSTALL_GITANNEX: git-annex
-    - ID: MacP310a3
+
+    - ID: MacP310-packages
       APPVEYOR_BUILD_WORKER_IMAGE: macos-monterey
       PY: 3.10
-      INSTALL_GITANNEX: git-annex
+      INSTALL_GITANNEX: git-annex -m datalad/packages
 
     # Test alternative Python versions
     - ID: Ubu20P39