pgsql: Rename injection points used in AIO tests

Rename injection points used in AIO tests

The format of the injection point names used by the AIO code does not
match the existing naming convention used everywhere else in the code,
so let's be consistent.  These points are used in test_aio.

Reviewed-by: Hayato Kuroda <kuroda.hayato@fujitsu.com>
Discussion: https://postgr.es/m/Z_yTB80bdu1sYDqJ@paquier.xyz

Branch
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master

Details
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https://git.postgresql.org/pg/commitdiff/114f7fa81c72637d75b574269f2076dcc1104e24

Modified Files
--------------
src/backend/storage/aio/aio.c           |  2 +-
src/backend/storage/aio/method_worker.c |  2 +-
src/test/modules/test_aio/test_aio.c    | 12 ++++++------
3 files changed, 8 insertions(+), 8 deletions(-)