pgsql: Fix tuple printing in error message of tuple routing for partiti

Fix tuple printing in error message of tuple routing for partitions

With correctly crafted DDLs, this could lead to disclosure of arbitrary
backend memory a user may have no right to access. This impacts only
REL_11_STABLE, as the issue has been introduced by 34295b8.

On HEAD, add regression tests to cover this issue in the future.

Author: Michael Paquier
Reviewed-by: Noah Misch
Security: CVE-2019-10129

Branch
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REL_11_STABLE

Details
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https://git.postgresql.org/pg/commitdiff/52635c276fe352276c157ccea36d7655729d328d

Modified Files
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src/backend/executor/execPartition.c | 8 ++++----
src/test/regress/expected/insert.out | 15 +++++++++++++++
src/test/regress/sql/insert.sql | 7 +++++++
3 files changed, 26 insertions(+), 4 deletions(-)