feat(externaldns): upgrade to 1.21.1, fix sources for installed CRDs

- Bump chart from 1.19.0 to 1.21.1 (app v0.19.0 -> v0.21.0)
- Remove gateway-tcproute source (TCPRoute CRD not installed)
- Add gateway-tlsroute source (TLSRoute CRD is installed)

apps/overlays/au-syd1/externaldns/values.yaml

@@ -25,8 +25,8 @@ sources:
   - service
   - ingress
   - gateway-httproute
+  - gateway-tlsroute
   - gateway-grpcroute
-  - gateway-tcproute
 
 # Environment variables for TSIG secret and algorithm from Vault
 env: