Change bp2build to reflect arm_isa refactor

We now rely on a `with_features` clause to effectively disable
thumb when `arm_isa_arm` is enabled. Thus, we no longer need to
add `-arm_isa_thumb` in bp2build.

Bug: 261733820
Test: Unit tests
Change-Id: I9da85834855b297a75097ce3a11e101f55bd53f4
diff --git a/cc/bp2build.go b/cc/bp2build.go
index cf5f74d..082e55f 100644
--- a/cc/bp2build.go
+++ b/cc/bp2build.go
@@ -492,7 +492,7 @@
 
 	instructionSet := proptools.StringDefault(props.Instruction_set, "")
 	if instructionSet == "arm" {
-		ca.features.SetSelectValue(axis, config, []string{"arm_isa_arm", "-arm_isa_thumb"})
+		ca.features.SetSelectValue(axis, config, []string{"arm_isa_arm"})
 	} else if instructionSet != "" && instructionSet != "thumb" {
 		ctx.ModuleErrorf("Unknown value for instruction_set: %s", instructionSet)
 	}