Remove locks from UpdateTimestampsCache

[hazzik]

See #2735

Hibernate has done [it] a long time ago to improve performance.

Possible breaking change:

In theory the read/write locking prevents that IsUpToDate would return stale data, but that holds true only when one instance of the application is running. In case multiple application instances are running then IsUpToDate may return stale data due to another application instance writing data at the same time. So we could remove the locking entirely as Hiberanate did or add a configuration setting for disabling it.

Originally posted by @maca88 in #2735 (comment)

[gokhanabatay]

@maca88 When we use redis pub/sub distributed cache in your implementation non cached entities causes too much syncronization events. Think about a configuration in entity mapping Cache.Never() that tells this entity never cached with query cache or entity cache ever.

If this approach is ok I could implement this in NHibernate and FluentNHibernate libraries.
For performance needs this is absolutly necessary.

There is also locks in NHibernate.Caches.StackExchangeRedis.DistributedLocalCacheRegionStrategy

[gokhanabatay]

5.3.9 released but does not contains this pr, it was tagged as next minor am I missing something. @fredericDelaporte @hazzik

[fredericDelaporte]

Current minor is 5.3.x. Next minor will be 5.4.x, or 6.0.x if we decide to go for a next major instead.

[hazzik]

@gokhanabatay yes, this was for 5.4.x, because we cannot change the behavior or add new features in 5.3.x

[fredericDelaporte]

@gokhanabatay, in case you were not knowing, you can still use this feature by using the latest MyGet package.

[gokhanabatay]

@fredericDelaporte thanks we are using myget latest nhibernate package for performance needs.