Define the bazel_metrics directory in $OUT.

$OUT/bazel_metrics directory is created in order to dump the
set of bazel profile files being created from a single build
execution. The directory is created from soong_ui.

Bug: b/173028918
Test: * m nothing and check out dir that there is no bazel_metrics dir.
      * USE_BAZEL=1 and checked out/bazel_metrics was created.
      * Ran m nothing and verified that out/bazel_metrics directory is
        deleted to ensure no metrics is uploaded or collected from the
	pipeline.

Change-Id: I1d3c2471065fae6931f35cef7f0f35fd84f76bef

ui/build/config.go

@@ -274,6 +274,16 @@ func NewConfig(ctx Context, args ...string) Config {
 		}
 	}
 
+	bpd := shared.BazelMetricsDir(ret.OutDir())
+	if err := os.RemoveAll(bpd); err != nil {
+		ctx.Fatalf("Unable to remove bazel profile directory %q: %v", bpd, err)
+	}
+	if ret.UseBazel() {
+		if err := os.MkdirAll(bpd, 0777); err != nil {
+			ctx.Fatalf("Failed to create bazel profile directory %q: %v", bpd, err)
+		}
+	}
+
 	c := Config{ret}
 	storeConfigMetrics(ctx, c)
 	return c