pgsql: Remove GlobalVisTestNonRemovable[Full]Horizon, not used anymore

Remove GlobalVisTestNonRemovable[Full]Horizon, not used anymore

GlobalVisTestNonRemovableHorizon() was only used for the implementation of
snapshot_too_old, which was removed in f691f5b80a8. As using
GlobalVisTestNonRemovableHorizon() is not particularly efficient, no new uses
for it should be added. Therefore remove.

Discussion: https://postgr.es/m/20240415185720.q4dg4dlcyvvrabz4@awork3.anarazel.de

Branch
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master

Details
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https://git.postgresql.org/pg/commitdiff/3ab8cf92754d5ee4390af4e4840fb45d5bc25007

Modified Files
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src/backend/storage/ipc/procarray.c | 30 ------------------------------
src/include/utils/snapmgr.h         |  2 --
2 files changed, 32 deletions(-)