Fix custom domain's env variable name (#10092)

deploy/docker/scripts/renew-certificate.sh

@@ -9,11 +9,10 @@ if [[ -f /appsmith-stacks/configuration/docker.env ]]; then
 	set +o allexport
 fi
 
-if [[ -n $CUSTOM_DOMAIN ]]; then
-	#then run script
-	local data_path="/appsmith-stacks/data/certificate"
-	domain="$CUSTOM_DOMAIN"
-	local rsa_key_size=4096
+if [[ -n $APPSMITH_CUSTOM_DOMAIN ]]; then
+	data_path="/appsmith-stacks/data/certificate"
+	domain="$APPSMITH_CUSTOM_DOMAIN"
+	rsa_key_size=4096
 
 	certbot certonly --webroot --webroot-path="$data_path/certbot" \
 		--register-unsafely-without-email \
@@ -24,4 +23,4 @@ if [[ -n $CUSTOM_DOMAIN ]]; then
 	supervisorctl restart editor
 else
 	echo 'Custom domain not configured. Cannot enable SSL without a custom domain.' >&2
-fi
+fi