Merge bitcoin#26156: test: check that listdescriptors descriptor strings are sorted

810c3dc doc, rpc: mention that `listdescriptors` result is sorted by string representation (Sebastian Falbesoner)
d99af86 test: check that `listdescriptors` descriptor strings are sorted (Sebastian Falbesoner)

Pull request description:

  This small PR adds a test for the change introduced in PR bitcoin#25931 ("rpc: sort listdescriptors result", commit 5099624). The correctness of the test can easily be verified by commenting out the `std::sort` call in the `listdescriptors` RPC implementation:
  ```diff
  diff --git a/src/wallet/rpc/backup.cpp b/src/wallet/rpc/backup.cpp
  index 09c74ea..3ed1a69b26 100644
  --- a/src/wallet/rpc/backup.cpp
  +++ b/src/wallet/rpc/backup.cpp
  @@ -1829,9 +1829,11 @@ RPCHelpMan listdescriptors()
           });
       }

  +    /*
       std::sort(wallet_descriptors.begin(), wallet_descriptors.end(), [](const auto& a, const auto& b) {
           return a.descriptor < b.descriptor;
       });
  +    */

       UniValue descriptors(UniValue::VARR);
       for (const WalletDescInfo& info : wallet_descriptors) {

  ```
  leading to a fail of the functional test `wallet_listdescriptors.py`.

ACKs for top commit:
  jarolrod:
    ACK 810c3dc
  aureleoules:
    ACK 810c3dc

Tree-SHA512: 31770e3149b8a0251ecfa8662a2270c149f778eb910985f48a91d6a5d288b7b1c2244f9f1b798ebe3f1aa9f0b935cb4d6f12d5d28f78bcde3c4a61af76d11d0a

Author: MacroFake

src/wallet/rpc/backup.cpp

@@ -1760,7 +1760,7 @@ RPCHelpMan listdescriptors()
         },
         RPCResult{RPCResult::Type::OBJ, "", "", {
             {RPCResult::Type::STR, "wallet_name", "Name of wallet this operation was performed on"},
-            {RPCResult::Type::ARR, "descriptors", "Array of descriptor objects",
+            {RPCResult::Type::ARR, "descriptors", "Array of descriptor objects (sorted by descriptor string representation)",
             {
                 {RPCResult::Type::OBJ, "", "", {
                     {RPCResult::Type::STR, "desc", "Descriptor string representation"},

test/functional/wallet_listdescriptors.py

@@ -52,6 +52,10 @@ def run_test(self):
             assert item['range'] == [0, 0]
             assert item['timestamp'] is not None
 
+        self.log.info('Test that descriptor strings are returned in lexicographically sorted order.')
+        descriptor_strings = [descriptor['desc'] for descriptor in result['descriptors']]
+        assert_equal(descriptor_strings, sorted(descriptor_strings))
+
         self.log.info('Test descriptors with hardened derivations are listed in importable form.')
         xprv = 'tprv8ZgxMBicQKsPeuVhWwi6wuMQGfPKi9Li5GtX35jVNknACgqe3CY4g5xgkfDDJcmtF7o1QnxWDRYw4H5P26PXq7sbcUkEqeR4fg3Kxp2tigg'
         xpub_acc = 'tpubDCMVLhErorrAGfApiJSJzEKwqeaf2z3NrkVMxgYQjZLzMjXMBeRw2muGNYbvaekAE8rUFLftyEar4LdrG2wXyyTJQZ26zptmeTEjPTaATts'