lxcpp: spin wait added in attach tests
lxcpp: spin wait added in attach tests

[Feature]       attach tests do not wait for constant amount of time
[Cause]         N/A
[Solution]      N/A
[Verification]  LxcppContainerAttachSuite

Change-Id: I7c5c78960ef37dd612cae7441ee983506ed434ca

Samsung/vasum,Samsung/vasum,Samsung/vasum,Samsung/vasum