MAINT divide appveyor builds by 2 (scikit-learn#11582)

while still testing old and new python and 32 and 64 bitnesses

Author: ogrisel

appveyor.yml

@@ -17,10 +17,6 @@ environment:
     SKLEARN_SKIP_NETWORK_TESTS: 1
 
   matrix:
-    - PYTHON: "C:\\Python37"
-      PYTHON_VERSION: "3.7.0"
-      PYTHON_ARCH: "32"
-
     - PYTHON: "C:\\Python37-x64"
       PYTHON_VERSION: "3.7.0"
       PYTHON_ARCH: "64"
@@ -29,10 +25,6 @@ environment:
       PYTHON_VERSION: "2.7.8"
       PYTHON_ARCH: "32"
 
-    - PYTHON: "C:\\Python27-x64"
-      PYTHON_VERSION: "2.7.8"
-      PYTHON_ARCH: "64"
-
 
 # Because we only have a single worker, we don't want to waste precious
 # appveyor CI time and make other PRs wait for repeated failures in a failing