srm: Avoid use of legacy PnfsGetFileMetaDataMessage

Besides removing the use of a legacy message, the patch resolves
a race condition in the directory creation code for uploads. The
old code tried to optimize the kind of meta data that was fetched
from PnfsManager, however since several uploads may interact, this
optimization could lead to errors as one upload would fetch meta
data reused by another upload.

Target: trunk
Require-notes: no
Require-book: no
pnfsmanager: Drop legacy PnfsGetFileMetaDataMessage

Target: trunk
Require-notes: no
Require-book: no
pnfsmanager: Drop PnfsSetFileMetaDataMessage

The few places that still used it have been updated to use
PnfsSetFileAttributes.

Target: trunk
Require-notes: no
Require-book: no
pnfsmanager: Drop legacy FileMetaData class

Target: trunk
Require-notes: no
Require-book: no
pnfsmanager: Drop PnfsGetStorageInfoMessage

Updated httpd, replica manager, transfer managers, and srm
to use PnfsGetFileAttributes.

Target: trunk
Require-notes: no
Require-book: no