[3.x] Better logging around connection creation/closing

[avelanarius]

When debugging connection issues, the current logging is insufficient. An example snippet of logs from a real-world connection issue:

2023-07-26 20:50:48,073:[DEBUG]:[com.datastax.driver.core.Connection]:[cluster1-nio-worker-0]:[Connection[/XXX.XXX.XXX.XXX:9042-25729, inFlight=0, closed=false] Connection established, initializing transport]
2023-07-26 20:50:48,073:[DEBUG]:[com.datastax.driver.core.Connection]:[cluster1-nio-worker-0]:[Connection[/XXX.XXX.XXX.XXX:9042-25727, inFlight=0, closed=false] Connection established, initializing transport]
2023-07-26 20:50:48,073:[DEBUG]:[com.datastax.driver.core.Connection]:[cluster1-nio-worker-1]:[Connection[/XXX.XXX.XXX.XXX:9042-25728, inFlight=0, closed=false] Connection established, initializing transport]
2023-07-26 20:50:48,074:[DEBUG]:[com.datastax.driver.core.Connection]:[cluster1-nio-worker-0]:[Connection[/YYY.YYY.YYY.YYY:9042-8033, inFlight=0, closed=true] closing connection]
2023-07-26 20:50:48,074:[DEBUG]:[com.datastax.driver.core.Host.STATES]:[cluster1-nio-worker-0]:[[/YYY.YYY.YYY.YYY:9042] Connection[/YYY.YYY.YYY.YYY:9042-8033, inFlight=0, closed=true] closed, remaining = 42]
2023-07-26 20:50:48,074:[DEBUG]:[com.datastax.driver.core.Host.STATES]:[cluster1-nio-worker-0]:[[/YYY.YYY.YYY.YYY:9042] preparing to open 1 new connections, total = 43]
2023-07-26 20:50:48,075:[DEBUG]:[com.datastax.driver.core.Connection]:[cluster1-nio-worker-1]:[Connection[/YYY.YYY.YYY.YYY:9042-8062, inFlight=0, closed=false] Connection established, initializing transport]
2023-07-26 20:50:48,080:[DEBUG]:[com.datastax.driver.core.Host.STATES]:[cluster1-nio-worker-0]:[[/XXX.XXX.XXX.XXX:9042] Connection[/XXX.XXX.XXX.XXX:9042-25727, inFlight=0, closed=false] Transport initialized, connection ready]
2023-07-26 20:50:48,084:[DEBUG]:[com.datastax.driver.core.Host.STATES]:[cluster1-nio-worker-0]:[[/XXX.XXX.XXX.XXX:9042] Connection[/XXX.XXX.XXX.XXX:9042-25729, inFlight=0, closed=false] Transport initialized, connection ready]
2023-07-26 20:50:48,086:[DEBUG]:[com.datastax.driver.core.Host.STATES]:[cluster1-nio-worker-1]:[[/YYY.YYY.YYY.YYY:9042] Connection[/YYY.YYY.YYY.YYY:9042-8062, inFlight=0, closed=false] Transport initialized, connection ready]
2023-07-26 20:50:48,086:[DEBUG]:[com.datastax.driver.core.Host.STATES]:[cluster1-nio-worker-1]:[[/XXX.XXX.XXX.XXX:9042] Connection[/XXX.XXX.XXX.XXX:9042-25728, inFlight=0, closed=false] Transport initialized, connection ready]
2023-07-26 20:50:48,086:[DEBUG]:[com.datastax.driver.core.Connection]:[cluster1-nio-worker-1]:[Connection[/XXX.XXX.XXX.XXX:9042-25699, inFlight=0, closed=true] closing connection]
2023-07-26 20:50:48,086:[DEBUG]:[com.datastax.driver.core.Host.STATES]:[cluster1-nio-worker-1]:[[/XXX.XXX.XXX.XXX:9042] Connection[/XXX.XXX.XXX.XXX:9042-25699, inFlight=0, closed=true] closed, remaining = 41]
2023-07-26 20:50:48,086:[DEBUG]:[com.datastax.driver.core.Connection]:[cluster1-nio-worker-1]:[Connection[/XXX.XXX.XXX.XXX:9042-25700, inFlight=0, closed=true] closing connection]
2023-07-26 20:50:48,086:[DEBUG]:[com.datastax.driver.core.Host.STATES]:[cluster1-nio-worker-1]:[[/XXX.XXX.XXX.XXX:9042] Connection[/XXX.XXX.XXX.XXX:9042-25700, inFlight=0, closed=true] closed, remaining = 40]
2023-07-26 20:50:48,086:[DEBUG]:[com.datastax.driver.core.Connection]:[cluster1-nio-worker-1]:[Connection[/XXX.XXX.XXX.XXX:9042-25701, inFlight=0, closed=true] closing connection]
2023-07-26 20:50:48,086:[DEBUG]:[com.datastax.driver.core.Host.STATES]:[cluster1-nio-worker-1]:[[/XXX.XXX.XXX.XXX:9042] Connection[/XXX.XXX.XXX.XXX:9042-25701, inFlight=0, closed=true] closed, remaining = 39]
2023-07-26 20:50:48,086:[DEBUG]:[com.datastax.driver.core.Host.STATES]:[cluster1-nio-worker-1]:[[/XXX.XXX.XXX.XXX:9042] preparing to open 3 new connections, total = 42]
2023-07-26 20:50:48,087:[DEBUG]:[com.datastax.driver.core.Connection]:[cluster1-nio-worker-0]:[Connection[/XXX.XXX.XXX.XXX:9042-25730, inFlight=0, closed=false] Connection established, initializing transport]
2023-07-26 20:50:48,087:[DEBUG]:[com.datastax.driver.core.Connection]:[cluster1-nio-worker-1]:[Connection[/XXX.XXX.XXX.XXX:9042-25731, inFlight=0, closed=false] Connection established, initializing transport]

The logs are missing the reason for closing the connection making it hard to determine the root cause.