[PATCH] Follow same pattern in ErodingKeyedObjectPool#toString as in other pool objects

Hello!

In ErodingObjectPool, the toString method outputs: ErodingObjectPool

And in ErodingPerKeyKeyedObjectPool it outputs:
ErodingPerKeyKeyedObjectPool

However, in ErodingKeyedObjectPool, the factor has a different prefix: ErodingKeyedObjectPool

This proposed patch follows the same pattern as in the aforementioned pools and changes ErodingKeyedObjectPool#toString.

Please, note that POOL-244 contains tests that may fail due to this change, so during the merge it may be good to take a look at TestPoolUtils#testErodingPoolKeyedObjectPoolDefaultFactor to avoid build errors.