samples/../mcumgr/smp_svr: differentiate integration platform

Differentiate integration)platforms list per each sample test.
Removed sample.mcumg.smp_svr.bt_tiny as it can not fit in
nr51422 flash anymore, even with configuration tweeks.

Signed-off-by: Andrzej Puzdrowski <andrzej.puzdrowski@nordicsemi.no>