ci: consume Windows CI images from the internal registry

Now that the Windows build jobs push php-*_windows to
registry.ddbuild.io/ci/dd-trace-php/dd-trace-ci, point the tracer/package
generators at the internal registry instead of the Docker Hub mirror, matching
the Linux images. Re-applies what ce65269 reverted (the blocker - Windows not
pushed to the internal registry - is fixed by this PR). The httpbin-windows and
php-request-replayer-2.0-windows helper images stay on the mirror; they aren't
built here.

Author: realFlowControl

.gitlab/generate-package.php

@@ -63,7 +63,7 @@
 $windows_build_platforms = [
     [
         "triplet" => "x86_64-pc-windows-msvc",
-        "image_template" => "registry.ddbuild.io/images/mirror/datadog/dd-trace-ci:php-%s_windows",
+        "image_template" => "registry.ddbuild.io/ci/dd-trace-php/dd-trace-ci:php-%s_windows",
         "arch" => "amd64",
         "host_os" => "windows-msvc",
         "targets" => [

.gitlab/generate-tracer.php

@@ -119,7 +119,7 @@ function before_script_steps($with_docker_auth = false) {
   variables:
     CONTAINER_NAME: $CI_JOB_NAME_SLUG
     GIT_STRATEGY: none
-    IMAGE: "registry.ddbuild.io/images/mirror/datadog/dd-trace-ci:php-${PHP_MAJOR_MINOR}_windows"
+    IMAGE: "registry.ddbuild.io/ci/dd-trace-php/dd-trace-ci:php-${PHP_MAJOR_MINOR}_windows"
   script: |
 <?php windows_git_setup() ?>