test: feature_rbf.py: check specified wallet type availability

The test currently leads to a failure if in general wallet
support is compiled, but the library for the specified type
(BDB/SQLite) is not, i.e.  if started with the
`--legacy-wallet` parameter, but bitcoind is compiled
without BDB support.

Fix this by checking if the specified wallet type (BDB for
legacy wallet, SQLite for descriptor wallet) is available.

Also move the helper `is_specified_wallet_compiled()` to the
test framework's class BitcoinTestFramework first, so it can
be reused.

test/functional/feature_rbf.py

@@ -538,7 +538,7 @@ def test_rpc(self):
         assert_equal(json0["vin"][0]["sequence"], 4294967293)
         assert_equal(json1["vin"][0]["sequence"], 4294967295)
 
-        if self.is_wallet_compiled():
+        if self.is_specified_wallet_compiled():
             self.init_wallet(node=0)
             rawtx2 = self.nodes[0].createrawtransaction([], outs)
             frawtx2a = self.nodes[0].fundrawtransaction(rawtx2, {"replaceable": True})

test/functional/interface_bitcoin_cli.py

@@ -66,12 +66,6 @@ def cli_get_info_string_to_dict(cli_get_info_string):
 
 
 class TestBitcoinCli(BitcoinTestFramework):
-    def is_specified_wallet_compiled(self):
-        if self.options.descriptors:
-            return self.is_sqlite_compiled()
-        else:
-            return self.is_bdb_compiled()
-
     def set_test_params(self):
         self.setup_clean_chain = True
         self.num_nodes = 1

test/functional/test_framework/test_framework.py

@@ -886,6 +886,14 @@ def is_wallet_compiled(self):
         """Checks whether the wallet module was compiled."""
         return self.config["components"].getboolean("ENABLE_WALLET")
 
+    def is_specified_wallet_compiled(self):
+        """Checks whether wallet support for the specified type
+           (legacy or descriptor wallet) was compiled."""
+        if self.options.descriptors:
+            return self.is_sqlite_compiled()
+        else:
+            return self.is_bdb_compiled()
+
     def is_wallet_tool_compiled(self):
         """Checks whether bitcoin-wallet was compiled."""
         return self.config["components"].getboolean("ENABLE_WALLET_TOOL")