Increase testReadWriteProgram() timeout to 15 minutes

Extended the timeout of ApfIntegrationTest#testReadWriteProgram() to 15
minutes to accommodate devices with larger APF memory (e.g., 4K RAM).

Example run on a device with 4K APF RAM:
[1/1] android.net.cts.ApfIntegrationTest#testReadWriteProgram: PASSED (09m47.451s)

Bug: 346707554
Test: TH
Change-Id: I063abe285e061edf3a0d338ba7233a08be03c9b4
1 file changed