Fix hanging unit test

Since these tests perform actual binder interactions with rkpd, we
need to spin up the binder thread pool so that the callbacks have
a thread to run on.

Test: keystore2_test
Change-Id: If0f67661f915798722d2bf7f9c5072887048cae8
diff --git a/keystore2/src/rkpd_client.rs b/keystore2/src/rkpd_client.rs
index 039cb90..5eb16be 100644
--- a/keystore2/src/rkpd_client.rs
+++ b/keystore2/src/rkpd_client.rs
@@ -417,16 +417,16 @@
     }
 
     #[test]
-    #[ignore]
     fn test_get_rkpd_attestation_key() {
+        binder::ProcessState::start_thread_pool();
         let key = get_rkpd_attestation_key(&SecurityLevel::TRUSTED_ENVIRONMENT, 0).unwrap();
         assert!(!key.keyBlob.is_empty());
         assert!(!key.encodedCertChain.is_empty());
     }
 
     #[test]
-    #[ignore]
     fn test_get_rkpd_attestation_key_same_caller() {
+        binder::ProcessState::start_thread_pool();
         let sec_level = SecurityLevel::TRUSTED_ENVIRONMENT;
         let caller_uid = 0;
 
@@ -439,8 +439,8 @@
     }
 
     #[test]
-    #[ignore]
     fn test_get_rkpd_attestation_key_different_caller() {
+        binder::ProcessState::start_thread_pool();
         let sec_level = SecurityLevel::TRUSTED_ENVIRONMENT;
 
         // Different callers should be getting different keys.
@@ -452,8 +452,8 @@
     }
 
     #[test]
-    #[ignore]
     fn test_store_rkpd_attestation_key() {
+        binder::ProcessState::start_thread_pool();
         let sec_level = SecurityLevel::TRUSTED_ENVIRONMENT;
         let key = get_rkpd_attestation_key(&SecurityLevel::TRUSTED_ENVIRONMENT, 0).unwrap();