Stabilize 039_end_of_wal test.

Stabilize 039_end_of_wal test.

The first test was sensitive to the insert LSN after setting up the
catalogs, which depended on environmental things like the locales on the
OS and usernames.  Switch to a new WAL file before the first test, as a
simple way to put every computer into the same state.

Back-patch to all supported releases.

Reported-by: Anton Voloshin <[email protected]>
Reported-by: Nathan Bossart <[email protected]>
Reviewed-by: Tom Lane <[email protected]>
Reviewed-by: Nathan Bossart <[email protected]>
Discussion: https://postgr.es/m/b26aeac2-cb6d-4633-a7ea-945baae83dcf%40postgrespro.ru