ActiveSupport notifications improvements

[fallwith]

With #2610 we made a number of ActiveSupport notifications related improvements in response to a GTSE. That GTSE was closed out automatically due to lack of activity, but we anticipate it or a similar one coming back in the future. In the meantime, this issue will serve as a placeholder to remind of us of what work was done. If we hear back via a new GTSE, then we can obviously do what it takes to address it. Otherwise, we ought to still consider salvaging some of the work done for #2610 for the benefit of all Rails using customers.

In summary, #2610 delivered all of the following:

• Defined a new configuration parameter, :'instrumentation.active_support_notifications.active_support_events', to serve as an allowlist of ActiveSupport specific notifications (notifications related to the use of the ActiveSupport library itself; of course notifications themselves are defined by ActiveSupport, but this list is related to the usage of the gem itself).
  • By default, the list has every publicly (HTML) documented notification
  • Notifications absent from the allow list are not even subscribed to by the agent
• A static (frozen hash) map of notification to method name is defined to simplify and speed up method name gleaning
• Support for the 'message_serializer_fallback.active_support' was added. Currently the agent only supports 'cache_*' related notifications
• #delete_prefix and #delete_suffix were introduced to deliver the position related transformations proven out by @kaylareopelle to deliver a performance boost.

With or without hearing back on the GTSE, we ought to move forward with one or more items from this list. Ideally, we should also agree to queue up additional work to bring the relevant changes to our other notifications based instrumentations.

[workato-integration]

https://new-relic.atlassian.net/browse/NR-276833