Support MySQL multi-host and SRV connections

[verma-divyanshu-git]

What changed?

• Accept comma-separated MySQL TCP addresses and tcp+srv DNS SRV records.
• Resolve targets for each new connection and fail over across unavailable or read-only hosts.
• Keep TLS configuration pool-local while preserving the existing tls-custom setting.

Why?

This lets Temporal fail over between MySQL endpoints without requiring a load balancer or VIP.

Fixes #10171.

How did you test it?

• built
• run locally and tested manually
• covered by existing tests
• added new unit test(s)

Also ran race tests, changed-line lint, the MySQL persistence integration test, and a live endpoint failover test through a terminated TCP proxy.

Potential risks

This changes MySQL connection establishment. Existing single-host, password refresh, TLS, and read-only behavior remain covered by tests.

[CLAassistant]

All committers have signed the CLA.

[verma-divyanshu-git]

Hi @yycptt, this updates the MySQL connection path and preserves the password-refresh behavior added in #9879. When you have time, would you be willing to review it or route it to the right persistence owner? Thanks.