audio: Increase test timeout for VtsHalAudioTargetTest

Some tests in `VtsHalAudioCoreTargetTest` may run for a long
time because they test all combinations of stream configurations.
As a result, the test was timing out on partners' devices.
The partner has confirmed that increasing the timeout to
30 minutes fixes the problem.

Bug: 350998390
Test: atest VtsHalAudioCoreTargetTest
Change-Id: I5eddd19f14d49e88b71134d040ebfb06a1f2d375