Revert "stop padding new append vecs to page size (#33607)"

[steviez]

This reverts commit b7962a3.

Problem

#33607 and #33608 have broken CI for the tip of master

running 1 test
test accounts_db::tests::test_shrink_collect_simple ... FAILED

failures:

---- accounts_db::tests::test_shrink_collect_simple stdout ----
thread 'accounts_db::tests::test_shrink_collect_simple' panicked at accounts-db/src/accounts_db.rs:17401:33:
assertion `left == right` failed
  left: 272
 right: 4096
note: run with `RUST_BACKTRACE=1` environment variable to display a backtrace

These two commits were introduced in parallel, which means CI never previously ran with only one of the commits. Each individual commit on top of master passes CI, but the combination of the two fails

Summary of Changes

Revert #33607

[steviez]

FYI @jeffwashington

[jeffwashington]

crud, my bad.

[steviez]

Pushing early since all other CI is blocked at the moment, and I confirmed the previously failing unit test passes with this revert