fees: Log non-fatal errors as [warning], instead of info-level

Also, remove not needed and possibly redundant function name and class
names from the log string. Also, minimally reword the log messages.
Also, remove redundant trailing newlines from log messages, while
touching.

Author: MarcoFalke

src/policy/fees.cpp

@@ -979,7 +979,7 @@ bool CBlockPolicyEstimator::Write(AutoFile& fileout) const
         longStats->Write(fileout);
     }
     catch (const std::exception&) {
-        LogPrintf("CBlockPolicyEstimator::Write(): unable to write policy estimator data (non-fatal)\n");
+        LogWarning("Unable to write policy estimator data (non-fatal)");
         return false;
     }
     return true;
@@ -992,7 +992,7 @@ bool CBlockPolicyEstimator::Read(AutoFile& filein)
         int nVersionRequired, dummy;
         filein >> nVersionRequired >> dummy;
         if (nVersionRequired > CURRENT_FEES_FILE_VERSION) {
-            throw std::runtime_error(strprintf("up-version (%d) fee estimate file", nVersionRequired));
+            throw std::runtime_error{strprintf("File version (%d) too high to be read.", nVersionRequired)};
         }
 
         // Read fee estimates file into temporary variables so existing data
@@ -1001,7 +1001,7 @@ bool CBlockPolicyEstimator::Read(AutoFile& filein)
         filein >> nFileBestSeenHeight;
 
         if (nVersionRequired < CURRENT_FEES_FILE_VERSION) {
-            LogPrintf("%s: incompatible old fee estimation data (non-fatal). Version: %d\n", __func__, nVersionRequired);
+            LogWarning("Incompatible old fee estimation data (non-fatal). Version: %d", nVersionRequired);
         } else { // nVersionRequired == CURRENT_FEES_FILE_VERSION
             unsigned int nFileHistoricalFirst, nFileHistoricalBest;
             filein >> nFileHistoricalFirst >> nFileHistoricalBest;
@@ -1041,7 +1041,7 @@ bool CBlockPolicyEstimator::Read(AutoFile& filein)
         }
     }
     catch (const std::exception& e) {
-        LogPrintf("CBlockPolicyEstimator::Read(): unable to read policy estimator data (non-fatal): %s\n",e.what());
+        LogWarning("Unable to read policy estimator data (non-fatal): %s", e.what());
         return false;
     }
     return true;