packetbeat/protos{,/amqp}: fix transaction hash size constant (#36723)

The transaction hash size is currently calculated as 2⊕16 (18) which
is most likely not what was intended. The code entered the code base in
the initial import which does not have an associated review. However,
the symbol ^ signifies exponent in other languages, and XOR is almost never
what someone would use for defining a constant like this, so it is very
likely that the original author intended a 64Ki cache size.

(cherry picked from commit df10d97)

CHANGELOG.next.asciidoc

@@ -88,6 +88,7 @@ https://github.com/elastic/beats/compare/v8.8.1\...main[Check the HEAD diff]
 
 *Packetbeat*
 
+- Fix default cache size calculation. {pull}36723[36723]
 
 *Winlogbeat*
 

packetbeat/protos/amqp/amqp_structs.go

@@ -27,7 +27,7 @@ import (
 type amqpMethod func(*amqpMessage, []byte) (bool, bool)
 
 const (
-	transactionsHashSize = 2 ^ 16
+	transactionsHashSize = 1 << 16
 	transactionTimeout   = 10 * 1e9
 )
 

packetbeat/protos/protos.go

@@ -33,7 +33,7 @@ import (
 )
 
 const (
-	DefaultTransactionHashSize                 = 2 ^ 16
+	DefaultTransactionHashSize                 = 1 << 16
 	DefaultTransactionExpiration time.Duration = 10 * time.Second
 )