pgsql: Remove unnecessary BufferGetPage() calls in fsm_vacuum_page().

Remove unnecessary BufferGetPage() calls in fsm_vacuum_page().

Just noticed that these were quite redundant, since we're holding the
page address in a local variable anyway, and we have pin on the buffer
throughout.

Also improve a comment.

Branch
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master

Details
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https://git.postgresql.org/pg/commitdiff/2b1759e2675fc01d6945c9a5fa65c7d7121212f7

Modified Files
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src/backend/storage/freespace/freespace.c | 7 ++++---
1 file changed, 4 insertions(+), 3 deletions(-)