[MAINT] remove test install with python 2.7 workflow (#3768)

* try a github workflow to test install

* rm test in azure and gh

azure-pipelines.yml

@@ -169,35 +169,3 @@ jobs:
       :; set -o errexit
       python -c "import nilearn"
     displayName: 'Test that installation succeeded'
-
-
-- job: 'test_expected_to_fail_installation_on_linux'
-  pool:
-    vmImage: 'ubuntu-20.04'
-  strategy:
-    matrix:
-      Python27:
-        python.version: '2.7'
-    maxParallel: 4
-
-  steps:
-  - task: UsePythonVersion@0
-    inputs:
-      versionSpec: '$(python.version)'
-      architecture: 'x64'
-
-  - script: |
-      set -e
-      python -m pip install --upgrade pip
-      pip install --prefer-binary build
-    displayName: 'Install dependencies for building Nilearn'
-
-  - script: |
-      set -e
-      python -m build
-    displayName: 'Build Nilearn'
-
-  - script: |
-      set -e
-      pip install dist/nilearn-*-py3-none-any.whl 2>&1 | grep "^ERROR"
-    displayName: 'Attempt to install Nilearn from wheel (expected to fail)'