qa: disablewallet: Check that wallet is really disabled
qa: disablewallet: Check that wallet is really disabled

Summary:
Backport core's PR10361

Depends on D1154

Test Plan:
  ./test/functional/test_runner.py disablewallet

Reviewers: #bitcoin_abc, schancel

Reviewed By: #bitcoin_abc, schancel

Subscribers: teamcity

Differential Revision: https://reviews.bitcoinabc.org/D1155

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