Add new [lfs_client].BATCH_SIZE and [server].LFS_MAX_BATCH_SIZE config settings....

Add new [lfs_client].BATCH_SIZE and [server].LFS_MAX_BATCH_SIZE config settings. (#32307)

This contains two backwards-compatible changes:
* in the lfs http_client, the number of lfs oids requested per batch is
loaded from lfs_client#BATCH_SIZE and defaulted to the previous value of
20
* in the lfs server/service, the max number of lfs oids allowed in a
batch api request is loaded from server#LFS_MAX_BATCH_SIZE and defaults
to 'nil' which equates to the previous behavior of 'infinite'

This fixes #32306

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Signed-off-by: Royce Remer <royceremer@gmail.com>
Co-authored-by: wxiaoguang <wxiaoguang@gmail.com>