The go.mod.check target generates pkg/apis/go.mod from the root go.mod
and must remove the root-only replace directive that points
github.com/rook/rook/pkg/apis to ./pkg/apis. The sed pattern expected
the line to start with "replace", but the actual line is tab-indented
inside the replace block, so the directive was never removed.
Update the sed pattern to match optional leading whitespace and remove
the incorrect self-replace from pkg/apis/go.mod.
Signed-off-by: Malay Kumar Parida <mparida@redhat.com>