Merge bitcoin/bitcoin#25942: test: add ismine test for descriptor ScriptPubKeyMan

1b77db2 test: add `ismine` test for descriptor scriptpubkeyman (w0xlt)

Pull request description:

  Currently `src/wallet/test/ismine_tests.cpp` has tests for the legacy ScriptPubKeyMan only.
  This PR adds tests for the descriptor ScriptPubKeyMan.

ACKs for top commit:
  ishaanam:
    ACK 1b77db2
  achow101:
    ACK 1b77db2
  furszy:
    ACK 1b77db2 with a non-blocking comment.

Tree-SHA512: 977b5d1e71f9468331aeb4ebaf3708dd651f9f3018d4544a395b87ca6d7fb8bfa6d20acc1a4f6e096e240e81d30fb7a6e8add190e52536e7a3cb5a80f392883f

Author: achow101