Normalize timestamp time zones

[andrewkroh]

Index names that contain dates may be incorrect when the system timezone is not in UTC. The index name (<beatname>-%{+yyyy.MM.dd}) is generated based on the internal @timestamp value. The date formatter that converts the %{+yyyy.MM.dd} into a date doesn't do any conversion to UTC.

Some Beats may normalize their timestamps to UTC before publishing events and they will not be affected by this bug.

For confirmed bugs, please report:

• Version: 5.x, 6.0
• Operating System: all
• Steps to Reproduce: Use Beats on a system where the timezone is not configured to UTC.

[andrewkroh]

Branches that have been patched:

• master (6.x) - Normalize times to common.Time with UTC time zone #4658
• 5.5 - Cherry-pick #4658 to 5.5: Normalize times to common.Time with UTC time zone #4683
• 5.x - Cherry-pick #4658 to 5.x: Normalize times to common.Time with UTC time zone #4684