Active WAL tailing fails when WAL value compression is enabled

Depending on which compression codec is used, a short read of the compressed bytes can cause catastrophic errors that confuse the WAL reader. This problem can manifest when the reader is actively tailing the WAL for replication. The input stream's available() method sometimes lies so cannot be relied upon. To avoid these issues, when WAL value compression is enabled, ensure all bytes of the compressed value are read before submitting the payload to the decompressor.