Motivation:
An exception may occur between ByteBuf's allocation and release. For example:
```java
java.lang.OutOfMemoryError: Java heap space
at java.lang.String.<init>(String.java:325)
at io.netty.buffer.ByteBufUtil.decodeString(ByteBufUtil.java:838)
at io.netty.buffer.AbstractByteBuf.toString(AbstractByteBuf.java:1247)
at io.netty.buffer.AbstractByteBuf.toString(AbstractByteBuf.java:1242)
at io.netty.handler.proxy.HttpProxyHandler.<init>(HttpProxyHandler.java:105)
at io.netty.handler.proxy.HttpProxyHandler.<init>(HttpProxyHandler.java:90)
at io.netty.handler.proxy.HttpProxyHandler.<init>(HttpProxyHandler.java:85)
```
It may cause the ByteBuf variable authz and authzBase64's leak.
Modification:
Release the ByteBuf in a finally block as soon as possible.
Result:
Fix a potential ByteBuf leak.
0c3eae34ec