pgsql: Fix test instability introduced in e349c95d3e9 due to async dedu

Fix test instability introduced in e349c95d3e9 due to async deduplication.

The statement emitting notifies tried to make sure page boundaries were
crossed, but failed to do so reliably due to deduplication.

Reported-By: chap@anastigmatix.net
Discussion: https://postgr.es/m/20220407185408.n7dvsgqsb3q6uze7@alap3.anarazel.de

Branch
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master

Details
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https://git.postgresql.org/pg/commitdiff/dbe29b0d2c96f34b3f3222c6fc1710fcff065f18

Modified Files
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src/test/isolation/expected/stats.out   | 22 +++++++++++-----------
src/test/isolation/expected/stats_1.out | 22 +++++++++++-----------
src/test/isolation/specs/stats.spec     |  4 ++--
3 files changed, 24 insertions(+), 24 deletions(-)