Fixes https://github.com/spring-projects/spring-integration/issues/3826
By default, the `SimplePool` is used with an `Integer.MAX_VALUE` pool size.
There is a performance degradation in the `setPoolSize()` when we try to
decrease the pool size: the `while` for `permits.tryAcquire()` is too long
close to the current `Integer.MAX_VALUE` pool size
* Revise the logic in the `setPoolSize()` to use `Semaphore.reducePermits()`
instead of the loop.
* Change the calculation for a new pool size for the current pool state:
or it is a size of a new request, or iti s equal to the `inUse.size()`.
It will be reduced on subsequent `releaseItem()` calls
* Reduce the number of `available` according a new pool size based on the `inUse`.
So, if `inUse > newPoolSize`, the `available` is cleared.
Otherewise, it is reduced to the number which would give `newPoolSize` together
with the `inUse` size
**Cherry-pick to `5.5.x`**
6fe59a76aa