Fix error message related to end TLI in backup manifest

Fix error message related to end TLI in backup manifest

The code adding the WAL information included in a backup manifest is
cross-checked with the contents of the timeline history file of the end
timeline.  A check based on the end timeline, when it fails, reported
the value of the start timeline in the error message.  This error is
fixed to show the correct timeline number in the report.

This error report would be confusing for users if seen, because it would
provide an incorrect information, so backpatch all the way down.

Oversight in 0d8c9c1210c4.

Author: Man Zeng <zengman@halodbtech.com>
Discussion: https://postgr.es/m/tencent_0F2949C4594556F672CF4658@qq.com
Backpatch-through: 14