1853 fix use -z instead of eq when checking if variable is empty (yetanotherco#1854)

Co-authored-by: hexcow <way-scarp4u@icloud.com>

Author: Mechanix97

scripts/fund_operator_devnet.sh

@@ -1,7 +1,7 @@
 #!/bin/bash
 
 # Check that OPERATOR_ADDRESS is not empty
-if [[ "$OPERATOR_ADDRESS" -eq "" ]]; then
+if [[ -z "$OPERATOR_ADDRESS" ]]; then
   echo "OPERATOR_ADDRESS is empty, using default value 0xf39Fd6e51aad88F6F4ce6aB8827279cffFb92266"
   OPERATOR_ADDRESS=0xf39Fd6e51aad88F6F4ce6aB8827279cffFb92266
 fi;

scripts/mint_mock_token.sh

@@ -1,7 +1,7 @@
 #!/bin/bash
 
 # check that OPERATOR_ADDRESS is not empty
-if [[ "$OPERATOR_ADDRESS" -eq "" ]]; then
+if [[ -z "$OPERATOR_ADDRESS" ]]; then
   echo "OPERATOR_ADDRESS is empty, using default value 0xf39Fd6e51aad88F6F4ce6aB8827279cffFb92266"
   OPERATOR_ADDRESS="0xf39Fd6e51aad88F6F4ce6aB8827279cffFb92266"
 fi;
@@ -17,7 +17,7 @@ mock_token_address=$(cast call "$mock_strategy_address" "underlyingToken()")
 
 operator_address=$(cat "$1" | yq -r '.operator.address')
 
-if [[ "$mock_token_address" -eq "" ]]; then
+if [[-z  "$mock_token_address" ]]; then
   echo "Mock token address is empty, please deploy the contracts first"
   exit 1
 fi;

scripts/user_fund_payment_service_devnet.sh

@@ -1,7 +1,7 @@
 #!/bin/bash
 
 # Check that OPERATOR_ADDRESS is not empty
-if [[ "$USER_ADDRESS" -eq "" ]]; then
+if [[ -z "$USER_ADDRESS" ]]; then
   echo "USER_ADDRESS is empty, using default value 0xf39Fd6e51aad88F6F4ce6aB8827279cffFb92266"
   USER_ADDRESS=0xf39Fd6e51aad88F6F4ce6aB8827279cffFb92266
   USER_PRIVATE_KEY=0xac0974bec39a17e36ba4a6b4d238ff944bacb478cbed5efcae784d7bf4f2ff80