[Branch-2.8] Add log to print exception stack.

[Technoboy-]

Motivation

PersistentTopic#subscribe doesn't print other exceptions such as NPE. which could not help us to locate the cause of the problem.

Example stack

21:58:30.785 [pulsar-io-4-3] INFO  org.apache.pulsar.broker.service.ServerCnx - [/10.28.2.2:54474] Subscribing on topic persistent://public/product-full-prod/6827 / maestro-marek2
21:58:30.786 [pulsar-io-4-3] INFO  org.apache.pulsar.broker.service.persistent.PersistentTopic - [persistent://public/product-full-prod/6827][maestro-marek2] Creating non-durable subscription at msg id -1:-1:-1:-1
21:58:30.786 [pulsar-io-4-3] INFO  org.apache.bookkeeper.mledger.impl.NonDurableCursorImpl - [public/product-full-prod/persistent/6827] Created non-durable cursor read-position=88853:0 mark-delete-position=88853:-1
21:58:30.786 [pulsar-io-4-3] INFO  org.apache.bookkeeper.mledger.impl.ManagedLedgerImpl - [public/product-full-prod/persistent/6827] Opened new cursor: NonDurableCursorImpl{ledger=public/product-full-prod/persistent/6827, ackPos=88853:-1, readPos=88853:0}
21:58:30.786 [pulsar-io-4-3] INFO  org.apache.bookkeeper.mledger.impl.ManagedCursorImpl - [public/product-full-prod/persistent/6827-maestro-marek2] Rewind from 88853:0 to 88853:0
21:58:30.786 [pulsar-io-4-3] WARN  org.apache.pulsar.broker.service.ServerCnx - [/10.28.2.2:54474][persistent://public/product-full-prod/6827][maestro-marek2] Failed to create consumer: consumerId=1, null
java.util.concurrent.CompletionException: java.lang.NullPointerException
	at java.util.concurrent.CompletableFuture.encodeThrowable(CompletableFuture.java:314) ~[?:?]
	at java.util.concurrent.CompletableFuture.uniAcceptNow(CompletableFuture.java:757) ~[?:?]
	at java.util.concurrent.CompletableFuture.uniAcceptStage(CompletableFuture.java:731) ~[?:?]
	at java.util.concurrent.CompletableFuture.thenAccept(CompletableFuture.java:2108) ~[?:?]
	at org.apache.pulsar.broker.service.persistent.PersistentTopic.lambda$subscribe$14(PersistentTopic.java:762)
	at java.util.concurrent.CompletableFuture.uniAcceptNow(CompletableFuture.java:753) ~[?:?]
	at java.util.concurrent.CompletableFuture.uniAcceptStage(CompletableFuture.java:731) ~[?:?]
	at java.util.concurrent.CompletableFuture.thenAccept(CompletableFuture.java:2108) ~[?:?]
	at org.apache.pulsar.broker.service.persistent.PersistentTopic.subscribe(PersistentTopic.java:758) 
	at org.apache.pulsar.broker.service.ServerCnx.lambda$null$13(ServerCnx.java:1017) 
	at java.util.concurrent.CompletableFuture.uniComposeStage(CompletableFuture.java:1106) ~[?:?]
	at java.util.concurrent.CompletableFuture.thenCompose(CompletableFuture.java:2235) ~[?:?]
	at org.apache.pulsar.broker.service.ServerCnx.lambda$handleSubscribe$16(ServerCnx.java:988) 

[BewareMyPower]

I've fixed the broken branch-2.8 by cherry-picking #11668 and revert some wrong cherry-pick operations before. Please rebase to branch-2.8.