remove ATOM testnet token as it's no longer supported (#169)

Author: LeTamanoir

src/integrations/fb_signer.ts

@@ -18,7 +18,6 @@ export type AssetId =
   | "ETH_TEST5"
   | "ETH_TEST6"
   | "ETH"
-  | "ATOM_COS_TEST"
   | "ATOM_COS"
   | "OSMO_TEST"
   | "OSMO"

src/services/atom.ts

@@ -139,7 +139,7 @@ export class AtomService extends Service {
     };
     const fbNote = note ? note : "ATOM tx from @kilnfi/sdk";
     const signer = this.getFbSigner(integration);
-    const fbTx = await signer.sign(payload, this.testnet ? "ATOM_COS_TEST" : "ATOM_COS", fbNote);
+    const fbTx = await signer.sign(payload, "ATOM_COS", fbNote);
     const signature: string = fbTx.signedMessages![0].signature.fullSig;
     const { data } = await api.post<CosmosSignedTx>(`/v1/atom/transaction/prepare`, {
       pubkey: tx.data.pubkey,