REFACTOR(tekton): migrate from GitHub to Gitea

- Rename EventListener from github-listener to gitea-listener
- Rename TriggerBinding from github-push-binding to gitea-push-binding
- Update webhook secret to gitea-webhook-secret
- Rename credentials from github to gitea
- Update Ingress service name to el-gitea-listener
- Update Vault secret paths from github to gitea

tekton/ci-cd/manifests/secrets/gitea-credentials.yaml

@@ -1,7 +1,7 @@
 apiVersion: external-secrets.io/v1
 kind: ExternalSecret
 metadata:
-  name: github-credentials
+  name: gitea-credentials
   namespace: tekton-pipelines
 spec:
   refreshInterval: 1h
@@ -9,14 +9,14 @@ spec:
     kind: ClusterSecretStore
     name: vault-backend
   target:
-    name: github-credentials
+    name: gitea-credentials
     creationPolicy: Owner
   data:
     - secretKey: username
       remoteRef:
-        key: github
+        key: gitea
         property: username
     - secretKey: password
       remoteRef:
-        key: github
+        key: gitea
         property: password