fixed demo-dubbo balance or freeze_amount less than zero bug

[WYUSIG]

Make sure that:

• You have read the contribution guidelines.
• You submit test cases (unit or integration tests) that back your changes.
• Your local test passed mvn clean install -Dmaven.javadoc.skip=true.

[WYUSIG]

if AccountDTO#amount greater than database's balance and database's balance greater than zero, then database's balance will change to negative number, and will confirm

[WYUSIG]

if try step updates db's table row == 0, should throw Exception, if not do that it will confirm

[yu199195]

pls check ci .

[WYUSIG]

my local test passed mvn clean install -Dmaven.javadoc.skip=true , i don't know why github can't pass