Follow up fix for ATOM-13512 (#5689)

* Follow up fix for ATOM-13512
Update the file mask mapping in ImageBuilder.settings.
Change Reflectance.preset to use BC4 format since it only needs once channel.

Signed-off-by: Qing Tao <55564570+VickyAtAZ@users.noreply.github.com>

Code/Tools/AssetProcessor/native/utilities/assetUtils.h

@@ -238,7 +238,6 @@ namespace AssetUtilities
     // hashMsDelay is only for automated tests to test that writing to a file while it's hashing does not cause a crash.
     // hashMsDelay is not used in non-unit test builds.
     AZ::u64 GetFileHash(const char* filePath, bool force = false, AZ::IO::SizeType* bytesReadOut = nullptr, int hashMsDelay = 0);
-    inline constexpr AZ::u64 FileHashBufferSize = 1024 * 64;
 
     //! Adjusts a timestamp to fix timezone settings and account for any precision adjustment needed
     AZ::u64 AdjustTimestamp(QDateTime timestamp);