[CD14] Clarify wording on EJB timers before upgrade/migration

This issue was originally raised by vedpathakyb from an interaction with a customer.

The instructions for preparing for an upgrade[1] or migration[2] has the following wording for checking EJB timers.

The persistent timer data in data/timer-service-data must be checked to determine whether it is compatible. Before the upgrade, review the deployment- files in that directory to determine which timers are still in use.

The customer was confused as to what 'compatible' means. After clarifying with lthon, a better understanding would be something like:

users [will] want to understand what EJB times are active and make sure that, after upgrade, they all stayed intact.

The docs should be re-worded to clarify its meaning (esp. removing 'compatible', which is confusing).

I suggest something like:

The persistent timer data in `data/timer-service-data` must be checked to determine whether it is applicable after an upgrade. Before the upgrade, review the `deployment-` files in that directory to determine which timers are still in use.

[1] https://access.redhat.com/documentation/en-us/red_hat_jboss_enterprise_application_platform/7.1/html/patching_and_upgrading_guide/upgrading-jboss-eap#preparing_for_the_upgrade
[2] https://access.redhat.com/documentation/en-us/red_hat_jboss_enterprise_application_platform/7.1/html-single/migration_guide/#migrate_back_up_important_data_and_review_server_state