Merge bitcoin#25104: wallet: Change log interval to use steady_clock

bdc6881 wallet: Change log interval to use `steady_clock` (w0xlt)

Pull request description:

  This refactors the log interval variables to use `steady_clock` as it is best suitable for measuring intervals.

ACKs for top commit:
  laanwj:
    This makes sense. Code review ACK bdc6881
  dunxen:
    Code review ACK bdc6881

Tree-SHA512: 738b4aa45cef01df77102320f83096a0a7d0c63d7fcf098a8c0ab16b29453a87dc789c110105590e1e215d03499db1d889a94f336dcb385b6883c8364c9d39b7

Author: MacroFake

src/wallet/wallet.cpp

@@ -1939,8 +1939,10 @@ int64_t CWallet::RescanFromTime(int64_t startTime, const WalletRescanReserver& r
  */
 CWallet::ScanResult CWallet::ScanForWalletTransactions(const uint256& start_block, int start_height, std::optional<int> max_height, const WalletRescanReserver& reserver, bool fUpdate)
 {
-    int64_t nNow = GetTime();
-    int64_t start_time = GetTimeMillis();
+    using Clock = std::chrono::steady_clock;
+    constexpr auto LOG_INTERVAL{60s};
+    auto current_time{Clock::now()};
+    auto start_time{Clock::now()};
 
     assert(reserver.isReserved());
 
@@ -1967,8 +1969,8 @@ CWallet::ScanResult CWallet::ScanForWalletTransactions(const uint256& start_bloc
         if (block_height % 100 == 0 && progress_end - progress_begin > 0.0) {
             ShowProgress(strprintf("%s " + _("Rescanning...").translated, GetDisplayName()), std::max(1, std::min(99, (int)(m_scanning_progress * 100))));
         }
-        if (GetTime() >= nNow + 60) {
-            nNow = GetTime();
+        if (Clock::now() >= current_time + LOG_INTERVAL) {
+            current_time = Clock::now();
             WalletLogPrintf("Still rescanning. At block %d. Progress=%f\n", block_height, progress_current);
         }
 
@@ -2035,7 +2037,8 @@ CWallet::ScanResult CWallet::ScanForWalletTransactions(const uint256& start_bloc
         WalletLogPrintf("Rescan interrupted by shutdown request at block %d. Progress=%f\n", block_height, progress_current);
         result.status = ScanResult::USER_ABORT;
     } else {
-        WalletLogPrintf("Rescan completed in %15dms\n", GetTimeMillis() - start_time);
+        auto duration_milliseconds = std::chrono::duration_cast<std::chrono::milliseconds>(Clock::now() - start_time);
+        WalletLogPrintf("Rescan completed in %15dms\n", duration_milliseconds.count());
     }
     return result;
 }