pgsql: Fix operator naming in pg_trgm GUC option descriptions

Fix operator naming in pg_trgm GUC option descriptions

Descriptions of pg_trgm GUC options have % replaced with %% like it was
a printf-like format.  But that's not needed since they are just plain strings.
This commit fixed that.  Backpatch to last supported version since this error
present from the beginning.

Reported-by: Masahiko Sawada
Discussion: https://postgr.es/m/CAD21AoAgPKODUsu9gqUFiNqEOAqedStxJ-a0sapsJXWWAVp%3Dxg%40mail.gmail.com
Backpatch-through: 9.4

Branch
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master

Details
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https://git.postgresql.org/pg/commitdiff/b6987a885ba9216e1f4319441303ee115556922c

Modified Files
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contrib/pg_trgm/trgm_op.c | 6 +++---
1 file changed, 3 insertions(+), 3 deletions(-)