Restrict signing tests to recent eras

Quick workaround for failure in the Shelley era. The proper solution is
to also restrict the implementation to only work in recent eras, for
which a JIRA task was created.

Techincally, hiding this failure is a API breaking change, but it would
be /highly/, highly unlikely for any user to care about signing txs in
the Shelley era... with non-compatibile timelock scripts. Besides, the
preceding constructTx endpoint only works in recent eras.

lib/wallet/test/unit/Cardano/Wallet/Shelley/TransactionSpec.hs

@@ -504,28 +504,42 @@ spec = do
     distributeSurplusSpec
     estimateSignedTxSizeSpec
     describe "Sign transaction" $ do
-        spec_forAllEras
+        -- TODO [ADP-2849] The implementation must be restricted to work only in
+        -- 'RecentEra's, not just the tests.
+        spec_forAllRecentEras
             "signTransaction adds reward account witness when necessary"
             prop_signTransaction_addsRewardAccountKey
-        spec_forAllEras
+        spec_forAllRecentEras
             "signTransaction adds extra key witnesses when necessary"
             prop_signTransaction_addsExtraKeyWitnesses
-        spec_forAllEras
+        spec_forAllRecentEras
             "signTransaction adds tx in witnesses when necessary"
             prop_signTransaction_addsTxInWitnesses
-        spec_forAllEras
+        spec_forAllRecentEras
             "signTransaction adds collateral witnesses when necessary"
             prop_signTransaction_addsTxInCollateralWitnesses
-        spec_forAllEras
+        spec_forAllRecentEras
             "signTransaction never removes witnesses"
             prop_signTransaction_neverRemovesWitnesses
-        spec_forAllEras
+        spec_forAllRecentEras
             "signTransaction never changes tx body"
             prop_signTransaction_neverChangesTxBody
-        spec_forAllEras
+        spec_forAllRecentEras
             "signTransaction preserves script integrity"
             prop_signTransaction_preservesScriptIntegrity
 
+spec_forAllRecentEras
+    :: Testable prop => String -> (AnyCardanoEra -> prop) -> Spec
+spec_forAllRecentEras description p =
+    describe description $
+    forAllRecentEras'
+        $ \(AnyCardanoEra era) -> it (show era)
+        $ property
+        $ p (AnyCardanoEra era)
+  where
+    forAllRecentEras' f = forAllRecentEras $ \(AnyRecentEra recentEra) ->
+        f $ AnyCardanoEra $ WriteTx.cardanoEraFromRecentEra recentEra
+
 spec_forAllEras
     :: Testable prop => String -> (AnyCardanoEra -> prop) -> Spec
 spec_forAllEras description p =