pgsql: Correct obsolete nbtree recovery comments.

Correct obsolete nbtree recovery comments.

Commit 40dae7ec537, which made the handling of interrupted nbtree page
splits more robust, removed an nbtree-specific end-of-recovery cleanup
step.  This meant that it was no longer possible to complete an
interrupted page split during recovery.  However, a reference to
recovery as a reason for using a NULL stack while inserting into a
parent page was missed.  Remove the reference.

Remove a similar obsolete reference to recovery that was introduced much
more recently, as part of the btree fastpath optimization enhancement
that made it into Postgres 11 (commit 2b272734, and follow-up commits).

Backpatch: 11-, where the fastpath optimization was introduced.

Branch
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master

Details
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https://git.postgresql.org/pg/commitdiff/60f3cc9553c7ea7a1cc61bcd1efe51537f31e531

Modified Files
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src/backend/access/nbtree/nbtinsert.c | 12 ++++++------
1 file changed, 6 insertions(+), 6 deletions(-)