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_13_STABLE

Details
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https://git.postgresql.org/pg/commitdiff/ac2303aa0386d2fa26cc3e237076b49827b39d6a

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(-)