ipc/default_authorizer_test: Change use of v23.Init to testContext().

Test files in package ipc should be using testContext().
The reason this was working before was somewhat lucky:
Files in package ipc_test were importing a profile which made
this automatically.
I am working on a way for this packages tests to be cleaner so
we don't have these weird profile issues.

Change-Id: I2b19d8180b678367f3e3462b9ac856d16aadd9df
diff --git a/profiles/internal/ipc/default_authorizer_test.go b/profiles/internal/ipc/default_authorizer_test.go
index c018f27..1e27287 100644
--- a/profiles/internal/ipc/default_authorizer_test.go
+++ b/profiles/internal/ipc/default_authorizer_test.go
@@ -3,7 +3,6 @@
 import (
 	"testing"
 
-	"v.io/v23"
 	"v.io/v23/security"
 	tsecurity "v.io/x/ref/lib/testutil/security"
 )
@@ -74,8 +73,7 @@
 			U(bob, B(che, "family")),
 			true}, // {ali, bob/friend, che/friend} talking to {bob, che/family}
 	}
-	ctx, shutdown := v23.Init()
-	defer shutdown()
+	ctx := testContextWithoutDeadline()
 	for _, test := range tests {
 		err := authorizer.Authorize(&mockSecurityContext{
 			p: pali,