Remove ATRACE_TAG_APP from atrace's control

We control app tracing via the -a option, which system properties that
early app startup code inspects. This startup code ATRACE_TAG_APP
internally depending on the value of the properties derived from the
-a space, so letting users control the global value of ATRACE_TAG_APP
from atrace provides a false sense of control.

This CL removes the ability to set the global tag, directing user
attention to the -a option instead.

Test: code inspection
Bug:  77814899
Change-Id: If981ba302db27da1c9f1942cf54d400bd4672b73
(cherry picked from commit a5d41e659acc691c6352d1c739e4f5c4ff2be3a7)
diff --git a/cmds/atrace/atrace.cpp b/cmds/atrace/atrace.cpp
index 21d9ace..f65f4f8 100644
--- a/cmds/atrace/atrace.cpp
+++ b/cmds/atrace/atrace.cpp
@@ -105,7 +105,6 @@
     { "video",      "Video",            ATRACE_TAG_VIDEO, { } },
     { "camera",     "Camera",           ATRACE_TAG_CAMERA, { } },
     { "hal",        "Hardware Modules", ATRACE_TAG_HAL, { } },
-    { "app",        "Application",      ATRACE_TAG_APP, { } },
     { "res",        "Resource Loading", ATRACE_TAG_RESOURCES, { } },
     { "dalvik",     "Dalvik VM",        ATRACE_TAG_DALVIK, { } },
     { "rs",         "RenderScript",     ATRACE_TAG_RS, { } },