Revert "Skip WAL for new relfilenodes, under wal_level=minimal."
This reverts commit
cb2fd7eac285b1b0a24eeb2b8ed4456b66c5a09f. Per
numerous buildfarm members, it was incompatible with parallel query, and
a test case assumed LP64. Back-patch to 9.5 (all supported versions).
Discussion: https://postgr.es/m/
20200321224920.GB1763544@rfd.leadboat.com