Some code optimizations about BrokerContainerStartup

[cserwen]

BUG REPORT

1. Please describe the issue you observed:

• Some optimizations about BrokerContainerStartup.class

2. Please tell us about your environment:

3. Other information (e.g. detailed explanation, logs, related issues, suggestions on how to fix, etc):

• replace "c" with static field BROKER_CONTAINER_CONFIG_OPTION, others too.
• rename brokerConfig to containerConfig
• remove boolean param of createBrokerContainer which is useless.

[RongtongJin]

Merged