cleanup few unused headers

The following files had some unused headers and caught my eyes, so
cleaning them up:

```bash
programs/obfuscator/Obfuscator.cpp
src/Databases/DatabaseAtomic.cpp
```

programs/obfuscator/Obfuscator.cpp

@@ -14,7 +14,6 @@
 #include <DataTypes/DataTypeNullable.h>
 #include <DataTypes/DataTypeFactory.h>
 #include <Interpreters/Context.h>
-#include <DataStreams/IBlockInputStream.h>
 #include <DataStreams/IBlockOutputStream.h>
 #include <DataStreams/LimitBlockInputStream.h>
 #include <Common/SipHash.h>
@@ -31,7 +30,6 @@
 #include <ext/bit_cast.h>
 #include <memory>
 #include <cmath>
-#include <optional>
 #include <unistd.h>
 #include <boost/program_options/options_description.hpp>
 #include <boost/program_options.hpp>

src/Databases/DatabaseAtomic.cpp

@@ -4,7 +4,6 @@
 #include <Poco/Path.h>
 #include <IO/ReadHelpers.h>
 #include <IO/WriteHelpers.h>
-#include <Common/Stopwatch.h>
 #include <Parsers/formatAST.h>
 #include <Common/renameat2.h>
 #include <Storages/StorageMaterializedView.h>