This commit removes "subcloud migrate" command since
"subcloud-peer-group migrate" command can be re-executed to migrate
a single subcloud that failed to migrate in the previous attempt.
Test Plan:
PASS - Verify that "dcmanager subcloud migrate" and "dcmanager help
subcloud migrate" return an error (dcmanager: 'subcloud migrate'
is not a dcmanager command. See 'dcmanager --help'.)
Closes-Bug: 2049336
Change-Id: I793bee7d680d59a4d29a585c88c8c1689976ee1b
Signed-off-by: Zhang Rong(Jon) <rong.zhang@windriver.com>