[TRACKING ISSUE] Refactor client connection manager to simplify

The tracking issue for the Java side PR.

See https://github.com/hazelcast/hazelcast/pull/20806 for details.

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Most of the logic is turned into a single threaded one to
be able reason about the logic easily.
Important ones that is responsibility of the single thread
- Writing to and removing from activeConnections
- Checking if all connections are gone and initating new cluster
- Checking if cluster id has changed and initating failover
if necessary.

We still connect to other members in parallel because we mainly
want a fast start. We gave up on one thing. We no longer try to
open connection to all members while trying to connection back
to a cluster. This does not effect initial start since in the
initial start, we had to wait for initial connection and member-list
from it to be able to connect all members anyway.

Inizia leggendo la pull request lato Java collegata, hazelcast/hazelcast#20806, poiché questa tracking issue non indica alcun file o test. Usa le relative modifiche e la discussione per comprendere le responsabilità del connection-manager a thread singolo, quindi verifica se il comportamento elencato relativo alle connessioni, al cluster-ID e al failover è coperto.

Scritto dal modello di indicizzazione a partire dal testo della issue.