Make volume slider in volume panel consistent with settings app

Screen recording:
- go/before-fix
- go/after-fix-and-flag-on

While in singleVolume mode, all volume sliders except Music stream will
be hidden in Settings app, e.g. call stream [1], alarm stream [2],
notification stream [3], ring stream [4]. This change adds the same
check in SysUI volume panel to be consistent with Settings app.

Otherwise although there are five streams in SysUI volume panel,
adjusting any of the volume slider will adjust all of the rest, which
is a wired behavior and seems like a UI bug.

[1] https://source.corp.google.com/h/googleplex-android/platform/superproject/main/+/main:packages/apps/Settings/src/com/android/settings/notification/CallVolumePreferenceController.java;l=38;bpv=0
[2] https://source.corp.google.com/h/googleplex-android/platform/superproject/main/+/main:packages/apps/Settings/src/com/android/settings/notification/AlarmVolumePreferenceController.java;l=36;bpv=0
[3] https://source.corp.google.com/h/googleplex-android/platform/superproject/main/+/main:packages/apps/Settings/src/com/android/settings/notification/NotificationVolumePreferenceController.java;l=100;bpv=0
[4] https://source.corp.google.com/h/googleplex-android/platform/superproject/main/+/main:packages/apps/Settings/src/com/android/settings/notification/SeparateRingVolumePreferenceController.java;l=89?q=RingVolumePreferenceController.java&sq=git:googleplex-android%2Fplatform%2Fsuperproject%2Fmain@main


Change-Id: Idd2c5cfe450aa6ff5409e6339fd7e33b24324750
Bug: b/373729625
Test: atest AudioSlidersInteractorTest, tested in desktop device with
single volume mode enabled
Flag: com.android.systemui.only_show_media_stream_slider_in_single_volume_mode
diff --git a/packages/SystemUI/aconfig/systemui.aconfig b/packages/SystemUI/aconfig/systemui.aconfig
index 651244a..c3dc65b 100644
--- a/packages/SystemUI/aconfig/systemui.aconfig
+++ b/packages/SystemUI/aconfig/systemui.aconfig
@@ -1507,3 +1507,13 @@
     purpose: PURPOSE_BUGFIX
   }
 }
+
+flag {
+   name: "only_show_media_stream_slider_in_single_volume_mode"
+   namespace: "systemui"
+   description: "When the device is in single volume mode, only show media stream slider and hide all other stream (e.g. call, notification, alarm, etc) sliders in volume panel"
+   bug: "373729625"
+   metadata {
+       purpose: PURPOSE_BUGFIX
+   }
+}