Change log messages for Windows stacktraces to use error() or severe() rather than log()

This would make it more obvious to our users and potentially easier for automated tools to detect that these messages are process-fatal.

• https://github.com/mongodb/mongo/blob/026f69dbf4f98e91b499bde5cb4ce73c332e9549/src/mongo/util/exception_filter_win32.cpp#L137-L138
• https://github.com/mongodb/mongo/blob/026f69dbf4f98e91b499bde5cb4ce73c332e9549/src/mongo/util/exception_filter_win32.cpp#L160
• https://github.com/mongodb/mongo/blob/026f69dbf4f98e91b499bde5cb4ce73c332e9549/src/mongo/util/exception_filter_win32.cpp#L163
• https://github.com/mongodb/mongo/blob/026f69dbf4f98e91b499bde5cb4ce73c332e9549/src/mongo/util/exception_filter_win32.cpp#L174