[Enhancement⚡️] Add simple broker config templates (master and slave) under distribution/config/broker #3813

Summary

• Add ready-to-use broker configuration templates to simplify local setup and demos:
  • distribution/config/broker/broker-simple-master.toml (new)
  • distribution/config/broker/broker-simple-slave.toml (new)

Motivation

• Provide an out-of-the-box experience for running a single master or a master–slave pair without hand-crafting configs.
• Standardize default ports and paths for examples, CI, and docs (e.g., listenPort=10911, haListenPort=10912, storePathRootDir=/opt/rocketmq/store).
• Reduce friction for contributors validating features across modules (broker, namesrv, client examples).

Describe the Solution You'd Like

• Keep the two TOML templates in distribution/config/broker/ with minimal, sane defaults:
  • Master: brokerId=0, brokerRole=ASYNC_MASTER (default), flushDiskType=ASYNC_FLUSH, listen/HA ports 10911/10912.
  • Slave: brokerId>0 (e.g., 1), brokerRole=SLAVE, haMasterAddress set to the master’s HA port, same store path by default.
• Include brief comments in-place to hint valid enum values and typical adjustments (cluster name, broker name, storage paths).

Describe Alternatives You've Considered

• Relying only on README snippets (harder to copy correctly, not executable).
• Generating configs via a CLI command (could be added later; templates are simpler to start with).

Additional Context

• Current additions detected in the working tree:
  • distribution/config/broker/broker-simple-master.toml
  • distribution/config/broker/broker-simple-slave.toml
• Note: broker-simple-slave.toml presently has brokerRole set to "ASYNC_MASTER" while the filename suggests a slave profile. Suggest setting brokerRole to "SLAVE" for consistency and correctness. Example:
  • Expected in slave:
    brokerRole = "SLAVE"
    brokerId = 1
    haMasterAddress = "127.0.0.1:10912"

Happy to submit a follow-up PR to align the slave template and add a short README snippet on how to use these templates with namesrv and broker processes.