Fix admin remove task command for timer queue

[yycptt]

We have an admin command for removing transfer, timer, and replication tasks. The command works for transfer and replication task, but for timer task, it won't delete anything.

The reason is that the cass query the command runs is using defaultVisibilityTimeout as the value for the visibility_ts field. This is true for transfer and replication task, but not timer task. The visibility_ts field for time task contains the actual time that timer should fire.

There're three things we need to do:

• When initializing logger for tasks, add a tag for visibility timestamp
• Modify the remove task CLI command so that it will take visibility timestamp as an option.
• Change the handler of remove task API to use the value. If visibility timestamp is not specified in the request, then use the default value. This is the case for transfer and replication task.

[yycptt]

Consider also implement this command for sql: #2479