VCN: Ignore packet loss detection when there is too few traffic

When the expected received packet number is smaller than 10, the
packet loss detection result will be ignored because the sample
size is too small to ensure a reliable result.

This patch also fixes the bug where the detector does not update
ths packet loss threshold when carrier config updates

Bug: 332598276
Test: atest FrameworksVcnTests && atest CtsVcnTestCases
Change-Id: Iccc47e83c48699d139029420572e2a2616c357cd