fix: move connections on reload even when a replica is removed

[jkaczman]

Previously, if a reload occurred, and if a replica was removed, all connections for all Pools (whether affiliated or not with the removed replica), would not be moved to the new Pools.

This is because Cluster::can_move_conns_to asserted that every existing Pool (address) must be present in the new configuration before attempting to move any.

To fix this,

• I removed all the upfront has_compatible_address_with checks, and since LoadBalancer::move_conns_to already uses has_compatible_address_with itself, no further changes were needed there.
• Additionally, I modified Address::compatible to account for database_number being different when a replica is removed.

Added a regression test for this. Removed some tests that asserted the old functionality.

Fixes https://github.com/pgdogdev/pgdog-enterprise/issues/615

[codecov]

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[levkk]

Nice!