Drop socket before client reconnect

[UkoeHB]

Problem

When a client goes through a reconnect cycle, it does not drop its socket until after reconnecting. This means messages can be stuck inside the socket sink's buffer indefinitely, with their message status hanging in MessageStatus::Sending. To improve responsiveness, it would be better to drop the socket immediately so message statuses update promptly.

Solution

• Refactor ClientActor::run() so the socket can be dropped before trying to reconnect.
• Clean up the implementation by refactoring into multiple functions.