CTS AAudio: Increase frames processed test time

Cuttlefish takes longer for the sample rate to stabilize.
Increase the process time to 5 seconds to reduce flakiness.

Bug: 354890110
Test: atest AAudioTests on cf_x86_64_phone-trunk_staging-userdebug
Flag: TEST_ONLY
Change-Id: I6407284aa9828bb139cc1b3e603eb65cc8e12eea