pgsql: Disallow infinite endpoints in generate_series() for timestamps.

Disallow infinite endpoints in generate_series() for timestamps.

Such cases will lead to infinite loops, so they're of no practical
value. The numeric variant of generate_series() already threw error
for this, so borrow its message wording.

Per report from Richard Wesley. Back-patch to all supported branches.

Discussion: https://postgr.es/m/91B44E7B-68D5-448F-95C8-B4B3B0F5DEAF@duckdblabs.com

Branch
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REL_10_STABLE

Details
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https://git.postgresql.org/pg/commitdiff/a1e4782a0bca3f19f05042c6f05675dbf4fcacc7

Modified Files
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src/backend/utils/adt/timestamp.c | 28 ++++++++++++++++++
src/test/regress/expected/timestamp.out | 49 +++++++++++++++++++++++++++++++
src/test/regress/expected/timestamptz.out | 49 +++++++++++++++++++++++++++++++
src/test/regress/sql/timestamp.sql | 15 ++++++++++
src/test/regress/sql/timestamptz.sql | 15 ++++++++++
5 files changed, 156 insertions(+)