txoo: compose env var set network not chain

- no need of using switch in entrypoint
- directly set the network instead of chain
Signed-off-by: Lakshya Singh <lakshay.singh1108@gmail.com>

txood/entrypoint.sh

@@ -1,20 +1,10 @@
 #!/bin/sh
 set -e
 
-LIGHTNING_NETWORK=""
-
-case $BITCOIN_CHAIN in
-    "test")    LIGHTNING_NETWORK=testnet ;;
-    "regtest") LIGHTNING_NETWORK=regtest ;;
-    "main")    LIGHTNING_NETWORK=bitcoin ;;
-    "signet")  LIGHTNING_NETWORK=signet ;;
-    *) echo "Invalid BITCOIN_CHAIN value: $BITCOIN_CHAIN" && exit 1 ;;
-esac
-
 if [ $(echo "$1" | cut -c1) = "-" ]; then
   echo "$0: assuming arguments for txood"
 
-  set -- txood --network $LIGHTNING_NETWORK "$@"
+  set -- txood --network $BITCOIN_NETWORK "$@"
 fi
 
 echo