qa: Extract rpc_timewait as test param

Summary:

Also increase it for wallet_dump and wallet_groups

Backport of core PR13837:
https://github.com/bitcoin/bitcoin/pull/13837/files

Note the the typo in wallet_dump.py is fixed (see
https://github.com/bitcoin/bitcoin/pull/15026/files)

Test Plan:

./test/functional/test_runner.py --extended

Reviewers: #bitcoin_abc, deadalnix

Reviewed By: #bitcoin_abc, deadalnix

Differential Revision: https://reviews.bitcoinabc.org/D4557