Merge #14023: Remove accounts rpcs

Summary:
bb08423d5ca866d4a139a3b57ff110d818d08b32 [doc] Add release notes for 'account' API removal (John Newbery)
1f4b865e57b4567270b1586bb1f348ab9106485d [wallet] Re-sort wallet RPC commands (John Newbery)
f0dc850bf698f7377797d7d68365d4fc79b0221c [wallet] Remove wallet account RPCs (John Newbery)

Pull request description:

This is the first part of #13825. It simply removes the RPC methods and tests.

#13825 touches lots of files and will require frequent rebasing.

Breaking it down for easier reviewing and fewer rebases.

Tree-SHA512: d29af8e7a035e4484e6b9bb56cb86592be0ec112d8ba4ce19c15d15366ff3086e89e99fca26b90c9d66f6d3e06894486d0f29948df0bb7dcb1e2c49c6887a85a

Backport of Core PR14023

Test Plan:

make check
ninja check
ninja check-functional
./bitcoind
./bitcoin-cli help

Verify the account rpcs were removed.

./bitcoin-cli help sendmany

Verify the change to sendmany help text.

Reviewers: O1 Bitcoin ABC, #bitcoin_abc, Fabien

Reviewed By: O1 Bitcoin ABC, #bitcoin_abc, Fabien

Subscribers: jasonbcox, Fabien

Differential Revision: https://reviews.bitcoinabc.org/D5316