pgsql: Fix memory leak in IndexScan node with reordering

Fix memory leak in IndexScan node with reordering

Fix ExecReScanIndexScan() to free the referenced tuples while emptying the
priority queue.  Backpatch to all supported versions.

Discussion: https://postgr.es/m/CAHqSB9gECMENBQmpbv5rvmT3HTaORmMK3Ukg73DsX5H7EJV7jw%40mail.gmail.com
Author: Aliaksandr Kalenik
Reviewed-by: Tom Lane, Alexander Korotkov
Backpatch-through: 10

Branch
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REL_14_STABLE

Details
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https://git.postgresql.org/pg/commitdiff/c76665edce3d4db4e509723e91742569e9f46817

Modified Files
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src/backend/executor/nodeIndexscan.c       |  6 +++++-
src/test/regress/expected/create_index.out | 27 +++++++++++++++++++++++++++
src/test/regress/sql/create_index.sql      |  4 ++++
3 files changed, 36 insertions(+), 1 deletion(-)