Revert "Sandbox soong_build by changing to root directory"

This reverts commit 05c25ccb4a.

Reason for revert: broke absolute OUT_DIR
Bug: 146437378

Change-Id: I523ed79d40e1c1ef040212ba794a7a084abea75d

android/register.go

@@ -84,9 +84,7 @@ type Context struct {
 }
 
 func NewContext() *Context {
-	ctx := &Context{blueprint.NewContext()}
-	ctx.SetSrcDir(absSrcDir)
-	return ctx
+	return &Context{blueprint.NewContext()}
 }
 
 func (ctx *Context) Register() {