Test multichannel AAC downmix using non-AAC specific key

Existing test was testing the AAC-specific key for channel count
of the decoded format. Repeat the test with codec-agnostic
KEY_MAX_OUTPUT_CHANNEL_COUNT key, testing the exact channel
count of the content, as well as an arbitrary value (99) much
larger than the actual channel count.

Bug: 204239218
Bug: 211823739
Test: atest DecoderTestAacFormat
Change-Id: I429d30604439a2ce97e70ba09316a5ac541ed77a
1 file changed