LU-6142 mgc: SPDX for management client

LU-6142 mgc: SPDX for management client

Convert from verbose license text to SDPX.

Test-Parameters: trivial
Signed-off-by: Timothy Day <timday@amazon.com>
Change-Id: I24de13d3c859710e439b880afd1c6024c2da8937
Reviewed-on: https://review.whamcloud.com/c/fs/lustre-release/+/55285
Tested-by: jenkins <devops@whamcloud.com>
Tested-by: Maloo <maloo@whamcloud.com>
Reviewed-by: Arshad Hussain <arshad.hussain@aeoncomputing.com>
Reviewed-by: James Simmons <jsimmons@infradead.org>
Reviewed-by: Oleg Drokin <green@whamcloud.com>