[Go 1.18] Improve error message when using the Kafka output with SHA-1 signed certificates

Go 1.18 rejects certificates signed with SHA-1: https://tip.golang.org/doc/go1.18#sha1

When Beats is built with Go 1.18 and configured to use the Kafka output with a SHA-1 signed certificate, the error message is the generic "Kafka has run out of available brokers to talk to". Ensure the underlying certificate error about an insecure signature mechanism is returned in this case to make debugging easier when users encounter this case. Likely this will require modifying our fork of sarama: https://github.com/elastic/sarama

To reproduce the problem, run the Kafka output on any branch that does not have the Go 1.18 fixes from the update PR (https://github.com/elastic/beats/pull/32574) using Go 1.18.