use registry mirror for docker-in-docker (#13438)

Co-authored-by: Lauris BH <lauris@nix.lv>

.drone.yml

@@ -681,6 +681,9 @@ steps:
         from_secret: docker_password
       username:
         from_secret: docker_username
+    environment:
+      PLUGIN_MIRROR:
+        from_secret: plugin_mirror
     when:
       event:
         exclude:
@@ -715,6 +718,9 @@ steps:
       tags: linux-arm64
       build_args:
         - GOPROXY=off
+    environment:
+      PLUGIN_MIRROR:
+        from_secret: plugin_mirror
     when:
       event:
         - pull_request
@@ -759,6 +765,9 @@ steps:
         from_secret: docker_password
       username:
         from_secret: docker_username
+    environment:
+      PLUGIN_MIRROR:
+        from_secret: plugin_mirror
     when:
       event:
         exclude:
@@ -778,6 +787,9 @@ steps:
         from_secret: docker_password
       username:
         from_secret: docker_username
+    environment:
+      PLUGIN_MIRROR:
+        from_secret: plugin_mirror
     when:
       event:
         exclude: