Add --skip-soong-tests argument to soong_ui and use it in multiproduct_kati

There is no need for multiproduct_kati to run the tests for
every product, they don't vary by product config. --skip-soong-tests
can also be used for local development to run soong_build even if
the tests don't pass.

Bug: 156428456
Test: m --skip-soong-tests nothing
Change-Id: I9c00e3d1b6e51d17bb290339c3f124d4d1c9e69f

ui/build/soong.go

@@ -38,7 +38,12 @@ func runSoong(ctx Context, config Config) {
 		ctx.BeginTrace(metrics.RunSoong, "blueprint bootstrap")
 		defer ctx.EndTrace()
 
-		cmd := Command(ctx, config, "blueprint bootstrap", "build/blueprint/bootstrap.bash", "-t", "-n")
+		args := []string{"-n"}
+		if !config.skipSoongTests {
+			args = append(args, "-t")
+		}
+
+		cmd := Command(ctx, config, "blueprint bootstrap", "build/blueprint/bootstrap.bash", args...)
 		cmd.Environment.Set("BLUEPRINTDIR", "./build/blueprint")
 		cmd.Environment.Set("BOOTSTRAP", "./build/blueprint/bootstrap.bash")
 		cmd.Environment.Set("BUILDDIR", config.SoongOutDir())