Add format value for NULL offload info

CTS case "android.media.audio.cts.DirectAudioProfilesForAttributesTest" fail due to create AudioTrack fail.
The case want to create AudioTrack with format=AUDIO_FORMAT_MP3 but no specific offload_info, AudioTrack::set() will use AUDIO_INFO_INITIALIZER as default offload_info which is_streaming is disabled, but next, SwAudioOutputDescriptor::open() will set is_streaming as enabled as default.
Not all platforms support streaming offload, may encounter create AudioTrack fail.

So, here add format value to offloadinfo in AudioTrack::set(), then is_streaming disabled value can be transmitted correctly.

Bug: 232048775
Test: cts android.media.audio.cts.DirectAudioProfilesForAttributesTest#testCreateDirectAudioTracksOnlyForGetDirectProfilesForAttributes
Change-Id: I077673aaa4d7f60dd1de280b5eab3ae4a6a45809
Merged-In: I077673aaa4d7f60dd1de280b5eab3ae4a6a45809