pgsql: Remove obsolete information schema tables

Remove obsolete information schema tables

Remove SQL_LANGUAGES, which was eliminated in SQL:2008, and
SQL_PACKAGES and SQL_SIZING_PROFILES, which were eliminated in
SQL:2011. Since they were dropped by the SQL standard, the
information in them was no longer updated and therefore no longer
useful.

This also removes the feature-package association information in
sql_feature_packages.txt, but for the time begin we are keeping the
information which features are in the Core package (that is, mandatory
SQL features). Maybe at some point someone wants to invent a way to
store that that does not involve using the "package" mechanism
anymore.

Discussion https://www.postgresql.org/message-id/flat/91334220-7900-071b-9327-0c6ecd012017%402ndquadrant.com

Branch
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master

Details
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https://git.postgresql.org/pg/commitdiff/2fc2a88e6722df40245d3ae2ec7f8fc1c6bf0596

Modified Files
--------------
doc/src/sgml/features.sgml | 9 +-
doc/src/sgml/information_schema.sgml | 216 ---------------------------
src/backend/catalog/information_schema.sql | 70 ---------
src/backend/catalog/sql_feature_packages.txt | 29 ----
src/backend/catalog/sql_features.txt | 4 -
src/include/catalog/catversion.h | 2 +-
src/test/regress/expected/sanity_check.out | 3 -
7 files changed, 4 insertions(+), 329 deletions(-)