What is the purpose of the change?

Fixes #16530.

After cd <service>, the QoS telnet command count <method> <times> read the times from args[2], which only exists when the service name is given as well. count sayHello 10 after cd therefore printed the statistics once instead of ten times.

This PR reads the times from the argument after the method in both forms. Without cd the parsing is unchanged.

Behavior change

• After cd, count <method> <times> now prints the statistics <times> times instead of once.
• After cd, a non-numeric second argument (for example count sayHello x) is now rejected with Illegal times x, must be integer., as it already is without cd, instead of being ignored. A third argument after cd is no longer used as the times.
• Without cd, nothing changes.

Verification

• New CountTelnetTest#testCountTimesWithDefaultService (count sayHello 2 with a default service) fails before the change (only one result is sent) and passes after it.
• Compared the old and new argument parsing for every combination of up to four arguments taken from a service name, a method name, a number, a non-number and an empty string, with and without a default service: without cd the result is the same for every input; with cd it differs only when the first argument is not a number and there are at least two arguments.
• mvn verify -pl dubbo-plugin/dubbo-qos: 108 tests, 0 failures (5 skipped, the @Disabled GenericServiceTest); spotless and checkstyle are clean.
• End to end, a provider with QoS enabled, commands sent over telnet:

Checklist

• Make sure there is a GitHub_issue field for the change.
• Write a pull request description that is detailed enough to understand what the pull request does, how, and why.
• Write necessary unit-test to verify your logic correction. If the new feature or significant change is committed, please remember to add sample in dubbo samples project.
• Make sure gitHub actions can pass. Why the workflow is failing and how to fix it?