scripted-diff: Replace MilliSleep with UninterruptibleSleep

This is safe because MilliSleep is never executed in a boost::thread,
the only type of thread that is interruptible.

* The RPC server uses std::thread
* The wallet is either executed in an RPC thread or the main thread
* bitcoin-cli, benchmarks and tests are only one thread (the main thread)

-BEGIN VERIFY SCRIPT-
sed -i --regexp-extended -e 's/MilliSleep\((\S+)\);/UninterruptibleSleep(std::chrono::milliseconds{\1});/g' $(git grep -l MilliSleep)
-END VERIFY SCRIPT-

src/wallet/db.cpp

@@ -756,7 +756,7 @@ bool BerkeleyBatch::Rewrite(BerkeleyDatabase& database, const char* pszSkip)
                 return fSuccess;
             }
         }
-        MilliSleep(100);
+        UninterruptibleSleep(std::chrono::milliseconds{100});
     }
 }
 
@@ -887,7 +887,7 @@ bool BerkeleyDatabase::Backup(const std::string& strDest)
                 }
             }
         }
-        MilliSleep(100);
+        UninterruptibleSleep(std::chrono::milliseconds{100});
     }
 }