Unit tests w/dynamic content to "dynamic-presubmit"

put unit tests that need dynamic content into a "dynamic-presubmit"
grouping so that we can run them with proper flags.

Bug: 167284748
Test: atest --include-subdir frameworks/av/media:dynamic-presubmit \
       -- --enable-module-dynamic-download=true
Change-Id: I39f9373ab1f543dacfae6b420a6969e1603b25dd