cleanup: Drop additional docker files

Since the build was moved to ko.build I believe these are not necessary
anymore.

Signed-off-by: Manuel Rüger <manuel@rueg.eu>

.dockerignore

@@ -1,15 +0,0 @@
-# Git Related Items
-.git
-.github
-.gitignore
-
-# CI Related Items
-.travis.yml
-cloudbuild.yaml
-.golangci.yml
-.zappr.yaml
-
-# Other
-docs
-OWNERS
-vendor

.github/dependabot.yml

@@ -27,11 +27,3 @@ updates:
       dev-dependencies:
         patterns:
           - "*"
-  - package-ecosystem: "docker" # Keep Docker dependencies up to date
-    directory: "/"
-    schedule:
-      interval: "daily"
-    groups:
-      dev-dependencies:
-        patterns:
-          - "*"

.ko.yaml

@@ -8,4 +8,3 @@ builds:
   - -s
   - -w
   - -X sigs.k8s.io/external-dns/pkg/apis/externaldns.Version={{.Env.VERSION}}
-