time: fix time zone parsing when format includes time zone seconds
The current implementation fails to parse a time string with a "Z"
time zone using a time format that includes time zone seconds. This
fix correctly parses the "Z" time zone for any Z-base time format
that includes seconds (i.e. "Z070000" or "Z07:00:00").
Fixes #68263
Change-Id: Idf8fa06b5f96383f050c4ffbd2bc5804fd408650
Reviewed-on: https://go-review.googlesource.com/c/go/+/595897
Auto-Submit: Ian Lance Taylor <iant@google.com> Reviewed-by: Ian Lance Taylor <iant@google.com>
LUCI-TryBot-Result: Go LUCI <golang-scoped@luci-project-accounts.iam.gserviceaccount.com> Reviewed-by: Than McIntosh <thanm@google.com>