Merge #16117: util: Replace boost sleep with std sleep

fae86c38bc util: Remove unused MilliSleep (MarcoFalke)
fa9af06d91 scripted-diff: Replace MilliSleep with UninterruptibleSleep (MarcoFalke)
fa4620be78 util: Add UnintrruptibleSleep (MarcoFalke)

Pull request description:

  We don't use the interruptible feature of boost's sleep anywhere, so replace it with the sleep in `std::thread`

ACKs for top commit:
  ajtowns:
    ACK fae86c38bc quick code review
  practicalswift:
    ACK fae86c38bc -- patch looks correct
  sipa:
    Concept and code review ACK fae86c38bc
  fanquake:
    ACK fae86c38bc - note that an instance of `DHAVE_WORKING_BOOST_SLEEP_FOR` was missed in the [linter](https://github.com/bitcoin/bitcoin/blob/master/test/lint/extended-lint-cppcheck.sh#L69), but that can be cleaned up later.

Tree-SHA512: 7c0f8eb197664b9f7d9fe6c472c77d384f11c797c913afc31de4b532e3b4fd9ea6dd174f92062ff9d1ec39b25e0900ca7c597435add87f0f2477d9557204848c

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});
     }
 }