pgsql: Refactor code dedicated to index vacuuming in vacuumlazy.c

Refactor code dedicated to index vacuuming in vacuumlazy.c

The part in charge of doing the vacuum on all the indexes of a relation
was duplicated, with the same handling for progress reporting done.
While on it, update the progress reporting for heap vacuuming in the
subroutine doing the actual work, keeping the status update local. This
way, any future caller of lazy_vacuum_heap() does not have to worry
about doing any progress reporting update.

Author: Justin Pryzby, Michael Paquier
Discussion: https://postgr.es/m/20191120210600.GC30362@telsasoft.com

Branch
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master

Details
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https://git.postgresql.org/pg/commitdiff/1ab41a3c8edcf5d7751e61d6ab83bf43b494668b

Modified Files
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src/backend/access/heap/vacuumlazy.c | 96 ++++++++++++++++--------------------
1 file changed, 43 insertions(+), 53 deletions(-)