pgsql: Bump transaction/multixact ID warning limits to 100M.

Bump transaction/multixact ID warning limits to 100M.

These warning limits were last changed to 40M by commit cd5e82256d.
For the benefit of workloads that rapidly consume transactions or
multixacts, this commit bumps the limits to 100M.  This will
hopefully give users enough time to react.

Reviewed-by: Chao Li <li.evan.chao@gmail.com>
Reviewed-by: Shinya Kato <shinya11.kato@gmail.com>
Reviewed-by: wenhui qiu <qiuwenhuifx@gmail.com>
Discussion: https://postgr.es/m/aRdhSSFb9zZH_0zc%40nathan

Branch
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master

Details
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https://git.postgresql.org/pg/commitdiff/48f11bfa06c6bc15369a2a0c89f7594392e02e2d

Modified Files
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doc/src/sgml/maintenance.sgml          | 8 ++++----
src/backend/access/transam/multixact.c | 6 +++---
src/backend/access/transam/varsup.c    | 6 +++---
3 files changed, 10 insertions(+), 10 deletions(-)