fix: gateway config for agent mTLS

[luohoufu]

What does this PR do

This pull request includes several important changes to the agent_relay_gateway_config.dat file to update network binding, enable TLS, and use dynamic credentials for authentication.

Network configuration updates:

• Changed the network binding from 0.0.0.0:8081 to 0.0.0.0:8765 and enabled TLS for mTLS connection with config servers.

Authentication updates:

• Updated the basic authentication credentials in the flow section to use dynamic placeholders $[[SETUP_AGENT_USERNAME]] and $[[SETUP_AGENT_PASSWORD]] instead of hardcoded values.
• Updated the Elasticsearch configuration to use dynamic placeholders $[[SETUP_AGENT_USERNAME]] and $[[SETUP_AGENT_PASSWORD]] for basic authentication, and added $[[SETUP_ENDPOINTS]] for endpoints.

Rationale for this change

Standards checklist

• The PR title is descriptive
• The commit messages are semantic
• Necessary tests are added
• Updated the release notes
• Necessary documents have been added if this is a new feature
• Performance tests checked, no obvious performance degradation