Camera: Add preview delay for YUV single capture

testSingleCapture starts repeating request before capturing single
image. Depending on whether the single capture is started before the 1st
repeating request, or after the Nth repeating requests, the capture
latency could be very different.

Add preview delay to measure the latency in the steady state.

Test: vendor testing
Bug: 196803797
Change-Id: Ief6eac2a4e867def9fd086e984a7a0890fb496a1
1 file changed