Merge bitcoin/bitcoin#28027: test: Fixes and updates to wallet_backwards_compatibility.py for 25.0 and descriptor wallets

afd9a67 test: roundtrip wallet backwards compat downgrade (Andrew Chow)
bbf43c6 test: Add 25.0 to wallet backwards compatibiilty test (Andrew Chow)
538939e test: Run upgrade test on all nodes (Andrew Chow)
6d46990 test: Run downgrade test on descriptor wallets (Andrew Chow)
f158573 test: Add 0.21 tr() incompatibility test (Andrew Chow)
f41215c test: add logging 0.17 incompatibilities in wallet back compat (Andrew Chow)
71c03ae test: Refactor v19 addmultisigaddress test to be distinct (Andrew Chow)
53f35d0 test: Remove w1_v18 from wallet backwards compatibility (Andrew Chow)
313d665 test: Fix 0.16 wallet paths and downgrade test (Andrew Chow)
5d84693 test: Add helper functions for checking node versions (Andrew Chow)

Pull request description:

  It was somewhat surprising to me that wallet_backwards_compatibility.py did not catch #27915 since the purpose of the test is to find downgrade issues such as that. It turns out the test was deficient in several places when it came to testing descriptor wallets, as well as deficient in addition to failing to correctly test some releases.

  This PR fixes these test cases, adds more informative logging, slightly refactors the entire test in order to better test future versions, and adds a 25.0 node to the test.

  Notable changes:
  * The compatibility test with 0.16 should not have been passing. The wallets were being copied incorrectly for 0.16 and resulting in 0.16 creating new wallets rather than testing the target wallets.
  * The downgrade test will actually be run on descriptor wallets and it will test that downgrades are successful, and a subsequent upgrade is also successful. This catches #27915.
  * The upgrade and downgrade test will be run on all versions up to master, rather than just 0.16, 0.17, and 0.19.

ACKs for top commit:
  Sjors:
    re-ACK afd9a67
  furszy:
    ACK afd9a67

Tree-SHA512: dd2d85cab29a636da93020681c533534af4a9cda18d8550c9db9d8937719b3a225025966981c5d4d2f30486448a772b760f0e723a25ea6bc49df80387dc7b8b0

Author: fanquake