test: migrate e2e/auth to system tests and fix sign-batch (#22149)

(cherry picked from commit 4733fc1)

client/account_retriever.go

@@ -13,6 +13,26 @@ type Account interface {
 	GetSequence() uint64
 }
 
+type mockAccount struct {
+	addr []byte
+}
+
+func (m mockAccount) GetAddress() sdk.AccAddress {
+	return m.addr
+}
+
+func (m mockAccount) GetPubKey() cryptotypes.PubKey {
+	return nil
+}
+
+func (m mockAccount) GetAccountNumber() uint64 {
+	return 0
+}
+
+func (m mockAccount) GetSequence() uint64 {
+	return 0
+}
+
 // AccountRetriever defines the interfaces required by transactions to
 // ensure an account exists and to be able to query for account fields necessary
 // for signing.
@@ -32,8 +52,8 @@ type MockAccountRetriever struct {
 	ReturnAccNum, ReturnAccSeq uint64
 }
 
-func (mar MockAccountRetriever) GetAccount(_ Context, _ sdk.AccAddress) (Account, error) {
-	return nil, nil
+func (mar MockAccountRetriever) GetAccount(_ Context, address sdk.AccAddress) (Account, error) {
+	return mockAccount{addr: address}, nil
 }
 
 func (mar MockAccountRetriever) GetAccountWithHeight(_ Context, _ sdk.AccAddress) (Account, int64, error) {