Bug Report: Incorrect sync.Pool usage in compressed transaction payload handling

[mattlord]

Overview of the Issue

In #16328 we added usage of sync.Pool, however when putting the object back in the pool we used the wrong pool. Instead of using the statelessDocoderPool we were using another sync.Pool instance that also existed in the package: readersPool.

This caused the statelessDocoderPool to NOT be used, but worse than that it could cause a panic when the readersPool was used here IF --mysql-server-pool-conn-read-buffers was set (defaults to false): https://github.com/planetscale/vitess/blob/4522a0ad8930f3556627ec1ebbe69103f3b0fc01/go/mysql/conn.go#L290-L292

h/t to @mattrobenolt for noticing this mistake! :hear

Reproduction Steps

N/A

Binary Version

vtgate version Version: 22.0.0-SNAPSHOT

Operating System and Environment details

N/A

Log Fragments

No response