Fix the log level of not support Sse42Crc32C

Signed-off-by: xiaolong.ran <ranxiaolong716gmail.com>

### Motivation

When users are using Apache Pulsar, they will encounter the following error about `Sse42Crc32C`. But in fact it does not affect the correctness of Apache Pulsar use. But the error level log information will cause confusion for the user.
```
10:12:49.119 [pulsar-ordered-OrderedExecutor-0-0-EventThread] ERROR org.apache.bookkeeper.proto.checksum.CRC32CDigestManager - Sse42Crc32C is not supported, will use a slower CRC32C implementation.
```



### Changes

Replace the log level of `not support Sse42Crc32C` from error to warn.



Reviewers: Enrico Olivelli <eolivelli@gmail.com>, Sijie Guo <None>

This closes #2198 from wolfstudy/xiaolong/sse42Crc32C
diff --git a/bookkeeper-server/src/main/java/org/apache/bookkeeper/proto/checksum/CRC32CDigestManager.java b/bookkeeper-server/src/main/java/org/apache/bookkeeper/proto/checksum/CRC32CDigestManager.java
index 59dec3a..f12b547 100644
--- a/bookkeeper-server/src/main/java/org/apache/bookkeeper/proto/checksum/CRC32CDigestManager.java
+++ b/bookkeeper-server/src/main/java/org/apache/bookkeeper/proto/checksum/CRC32CDigestManager.java
@@ -32,6 +32,8 @@
 @Slf4j
 class CRC32CDigestManager extends DigestManager {
 
+    private static boolean nonSupportedMessagePrinted = false;
+
     private static final FastThreadLocal<MutableInt> currentCrc = new FastThreadLocal<MutableInt>() {
         @Override
         protected MutableInt initialValue() throws Exception {
@@ -41,8 +43,10 @@
 
     public CRC32CDigestManager(long ledgerId, boolean useV2Protocol, ByteBufAllocator allocator) {
         super(ledgerId, useV2Protocol, allocator);
-        if (!Sse42Crc32C.isSupported()) {
-            log.error("Sse42Crc32C is not supported, will use a slower CRC32C implementation.");
+
+        if (!Sse42Crc32C.isSupported() && !nonSupportedMessagePrinted) {
+            log.warn("Sse42Crc32C is not supported, will use a slower CRC32C implementation.");
+            nonSupportedMessagePrinted = true;
         }
     }