pgsql: Revert "Move page initialization from RelationAddExtraBlocks()t

Revert "Move page initialization from RelationAddExtraBlocks() to use."

This reverts commit fc02e6724f3ce069b33284bce092052ab55bd751 and
e6799d5a53011985d916fdb48fe014a4ae70422e.

Parts of the buildfarm error out with
ERROR: page %u of relation "%s" should be empty but is not
errors, and so far I/we do not know why. fc02e672 didn't fix the
issue.  As I cannot reproduce the issue locally, it seems best to get
the buildfarm green again, and reproduce the issue without time
pressure.

Branch
------
master

Details
-------
https://git.postgresql.org/pg/commitdiff/684200543b4cbfe1ac002c9962e90683d4ea4691

Modified Files
--------------
src/backend/access/heap/hio.c        | 31 ++++---------
src/backend/access/heap/vacuumlazy.c | 89 +++++++++++++-----------------------
2 files changed, 42 insertions(+), 78 deletions(-)