Remove emergency JMX config for nested DOM with Solr 7+

[obenkenobi]

Description

With respect to the previous issue with enhancing JMX metrics with Solr 7 and up, and the associated pull request, a new config was added to disable the feature. This is due to some new internal string formatting added to handle MBeans containing an object name with nested dom.

The new configuration here is as follows:

yaml:

# newrelic.yml snippet
common: &default_settings
  jmx:
    enable_iterated_objectname_Keys: true # default is true

system property:

-Dnewrelic.config.jmx.enable_iterated_objectname_Keys=true

environment variable:

NEW_RELIC_JMX_ENABLE_ITERATED_OBJECTNAME-KEYS=true

Acceptance Criteria

To remove the new JMX configuration as shown above and simplify any conditional checks and updates to tests due to the new config.

Additional context

This is not an officially documented configuration as the expectation here is anyone using Solr 7 and up will not need to disable the new internal syntax. Assuming no new issue pops up related to that syntax, we should later remove the config.

[workato-integration]

https://new-relic.atlassian.net/browse/NR-252050