add failure_store to beats monitoring template

[leehinman]

Add failure_store fields to monitoring templates.

Relates: elastic/beats#48068
Relates: elastic/beats#49452

[consulthys]

Thanks @leehinman that looks good! I have two comments:

1. You also need to increment STACK_MONITORING_REGISTRY_VERSION in MonitoringRegistryTemplate
2. I'm not sure you need to modify monitoring-es-mb.json unless you also modified Beats internal monitoring module

[leehinman]

1. You also need to increment STACK_MONITORING_REGISTRY_VERSION in MonitoringRegistryTemplate

Updated. Hopefully I got it right.

2. I'm not sure you need to modify monitoring-es-mb.json unless you also modified Beats internal monitoring module

The original change is elastic/beats#48068, and it means that all the beats that use elasticsearch for an output will collect the failure_store metric. And it should be reported by the vistor that reads the registry for libbeat.

[consulthys]

LGT Stack Monitoring