pgsql: Add more tests for corrupted data with pglz_decompress()

Add more tests for corrupted data with pglz_decompress()

Two cases fixed by 2b5ba2a0a141 were not covered, to emulate the
handling of corrupted data, for:
- set control bit with a valid 2-byte match tag where offset is 0.
- set control bit with a valid 2-byte match tag where offset exceeds
output written.

Oversight in 67d318e70402.

Reviewed-by: Ayush Tiwari <ayushtiwari.slg01@gmail.com>
Discussion: /messages/by-id/agF4xkIdRcrCIprs@paquier.xyz
Backpatch-through: 14

Branch
------
REL_15_STABLE

Details
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https://git.postgresql.org/pg/commitdiff/f4ba78081895d40ced104fc63914be7fd2e4372c

Modified Files
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src/test/regress/expected/compression_pglz.out | 12 ++++++++++++
src/test/regress/sql/compression_pglz.sql | 10 ++++++++++
2 files changed, 22 insertions(+)