wallet: Translate [default wallet] string in progress messages

Noticed while reviewing bitcoin#31287
(bitcoin#31287 (comment)) that the
[default wallet] part of progress messages remains untranslated while the rest
of the string is translated. Fix this in all places where Wallet::ShowProgress
(which has a cancel button) and chain::showProgress (which doesn't have a
cancel button) are called by making "default wallet" into a translated string.

src/wallet/rpc/backup.cpp

@@ -534,7 +534,7 @@ RPCHelpMan importwallet()
 
         // Use uiInterface.ShowProgress instead of pwallet.ShowProgress because pwallet.ShowProgress has a cancel button tied to AbortRescan which
         // we don't want for this progress bar showing the import progress. uiInterface.ShowProgress does not have a cancel button.
-        pwallet->chain().showProgress(strprintf("%s %s", pwallet->GetDisplayName(), _("Importing…").translated), 0, false); // show progress dialog in GUI
+        pwallet->chain().showProgress(pwallet->TranslatedMessage(_("Importing…")), 0, false); // show progress dialog in GUI
         std::vector<std::tuple<CKey, int64_t, bool, std::string>> keys;
         std::vector<std::pair<CScript, int64_t>> scripts;
         while (file.good()) {

src/wallet/wallet.cpp

@@ -1897,7 +1897,7 @@ CWallet::ScanResult CWallet::ScanForWalletTransactions(const uint256& start_bloc
                     fast_rescan_filter ? "fast variant using block filters" : "slow variant inspecting all blocks");
 
     fAbortRescan = false;
-    ShowProgress(strprintf("%s %s", GetDisplayName(), _("Rescanning…").translated), 0); // show rescan progress in GUI as dialog or on splashscreen, if rescan required on startup (e.g. due to corruption)
+    ShowProgress(TranslatedMessage(_("Rescanning…")), 0); // show rescan progress in GUI as dialog or on splashscreen, if rescan required on startup (e.g. due to corruption)
     uint256 tip_hash = WITH_LOCK(cs_wallet, return GetLastBlockHash());
     uint256 end_hash = tip_hash;
     if (max_height) chain().findAncestorByHeight(tip_hash, *max_height, FoundBlock().hash(end_hash));
@@ -1912,7 +1912,7 @@ CWallet::ScanResult CWallet::ScanForWalletTransactions(const uint256& start_bloc
             m_scanning_progress = 0;
         }
         if (block_height % 100 == 0 && progress_end - progress_begin > 0.0) {
-            ShowProgress(strprintf("%s %s", GetDisplayName(), _("Rescanning…").translated), std::max(1, std::min(99, (int)(m_scanning_progress * 100))));
+            ShowProgress(TranslatedMessage(_("Rescanning…")), std::max(1, std::min(99, (int)(m_scanning_progress * 100))));
         }
 
         bool next_interval = reserver.now() >= current_time + INTERVAL_TIME;
@@ -2009,7 +2009,7 @@ CWallet::ScanResult CWallet::ScanForWalletTransactions(const uint256& start_bloc
         WalletLogPrintf("Scanning current mempool transactions.\n");
         WITH_LOCK(cs_wallet, chain().requestMempoolTransactions(*this));
     }
-    ShowProgress(strprintf("%s %s", GetDisplayName(), _("Rescanning…").translated), 100); // hide progress dialog in GUI
+    ShowProgress(TranslatedMessage(_("Rescanning…")), 100); // hide progress dialog in GUI
     if (block_height && fAbortRescan) {
         WalletLogPrintf("Rescan aborted at block %d. Progress=%f\n", block_height, progress_current);
         result.status = ScanResult::USER_ABORT;

src/wallet/wallet.h

@@ -929,6 +929,14 @@ class CWallet final : public WalletStorage, public interfaces::Chain::Notificati
         return strprintf("[%s]", wallet_name);
     };
 
+    /** Return a translate message with the wallet name for use in ShowProgress. */
+    std::string TranslatedMessage(const bilingual_str& message)
+    {
+        std::string name{GetName()};
+        if (name.empty()) name = _("default wallet").translated;
+        return strprintf("[%s] %s", name, message.translated);
+    }
+
     /** Prepends the wallet name in logging output to ease debugging in multi-wallet use cases */
     template <typename... Params>
     void WalletLogPrintf(util::ConstevalFormatString<sizeof...(Params)> wallet_fmt, const Params&... params) const