* Update relation's stats in pg_class during vacuum full.

Hash index depends on estimation of numbers of tuples and pages of relations,
incorrect value could be a reason of significantly growing of index. Vacuum
full recreates heap and reindex all indexes before renewal stats. The patch
fixes that, so indexes will see correct values.

Backpatch to v10 only because earlier versions haven't usable hash index and
growing of hash index is a single user-visible symptom.

Author: Amit Kapila
Reviewed-by: Ashutosh Sharma, me
Discussion: https://www.postgresql.org/message-id/flat/20171115232922.5tomkxnw3iq6jsg7@inml.weebeastie.net

* Collect QE's relpages and reltuples to QD

And logic in swap_relation_files() to collect QE's relpages and reltuples to QD when doing vacuum full
Co-authored-by: NJimmy Yih <jyih@pivotal.io>
Co-authored-by: NAshwin Agrawal <aagrawal@pivotal.io>

* Add test

Add test to verify that relpages and reltuples has become proper numbers when vacuum full
Co-authored-by: NTaylor Vesely <tvesely@pivotal.io>

* Update PR pipeline failures
Reviewed-by: NAdam Berlin <aberlin@pivotal.io>
Reviewed-by: NAlexandra Wang <lewang@pivotal.io>
Reviewed-by: NJimmy Yih <jyih@pivotal.io>
Reviewed-by: NAshwin Agrawal <aagrawal@pivotal.io>
Reviewed-by: NTaylor Vesely <tvesely@pivotal.io>