pgsql: Add missing assign hook for GUC checkpoint_completion_target

Add missing assign hook for GUC checkpoint_completion_target

This is wrong since 88e9823, that has switched the WAL sizing
configuration from checkpoint_segments to min_wal_size and
max_wal_size. This missed the recalculation of the internal value of
the internal "CheckPointSegments", that works as a mapping of the old
GUC checkpoint_segments, on reload, for example, and it controls the
timing of checkpoints depending on the volume of WAL generated.

Most users tend to leave checkpoint_completion_target at 0.9 to smooth
the I/O workload, which is why I guess this has gone unnoticed for so
long, still it can be useful to tweak and reload the value dynamically
in some cases to control the timing of checkpoints.

Author: Bharath Rupireddy
Discussion: https://postgr.es/m/CALj2ACXgPPAm28mruojSBno+F_=9cTOOxHAywu_dfZPeBdybQw@mail.gmail.com
Backpatch-through: 11

Branch
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REL_14_STABLE

Details
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https://git.postgresql.org/pg/commitdiff/2e21e2857e5657b6867b337ddce5a22afce320c6

Modified Files
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src/backend/utils/misc/guc.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)