[ci] Remove the not used azure-pipelines.yml

We will use GitHub Actions instead, same infrastructure anyway, or even better, CircleCI's Windows support

azure-pipelines.yml

@@ -1,21 +0,0 @@
-pool:
-  vmImage: 'VS2017-Win2016'
-
-variables:
-  buildPlatform: 'x86'
-  buildConfiguration: 'Debug'
-  triplet: 'x86-windows'
-
-steps:
-- script: |
-    git clone https://github.com/Microsoft/vcpkg
-    cd vcpkg
-    .\bootstrap-vcpkg.bat
-    .\vcpkg integrate install
-    .\vcpkg install glib:x86-windows freetype:x86-windows cairo:x86-windows
-    cd ..
-    cmake -Bbuild -H. -DHB_HAVE_UNISCRIBE=ON -DHB_HAVE_DIRECTWRITE=ON -DHB_HAVE_GLIB=ON -DHB_HAVE_FREETYPE=ON -DHB_BUILD_UTILS=ON -G "%generator%" -DCMAKE_TOOLCHAIN_FILE=vcpkg/scripts/buildsystems/vcpkg.cmake ../
-    msbuild harfbuzz.sln /p:Configuration=Debug /p:Platform=Win32
-    cd build
-    ctest --output-on-failure -C Debug
-  displayName: Build and test