Reset all host configs *before* setting what we need

Not after :) This fixes the local server tests failing to SSL handshake.

src/objective-c/tests/InteropTestsLocalCleartext.m

@@ -48,10 +48,10 @@ static NSString * const kLocalCleartextHost = @"localhost:5050";
 }
 
 - (void)setUp {
+  [super setUp];
+
   // Register test server as non-SSL.
   [GRPCCall useInsecureConnectionsForHost:kLocalCleartextHost];
-
-  [super setUp];
 }
 
 @end

src/objective-c/tests/InteropTestsLocalSSL.m

@@ -48,13 +48,13 @@ static NSString * const kLocalSSLHost = @"localhost:5051";
 }
 
 - (void)setUp {
+  [super setUp];
+
   // Register test server certificates and name.
   NSBundle *bundle = [NSBundle bundleForClass:self.class];
   NSString *certsPath = [bundle pathForResource:@"TestCertificates.bundle/test-certificates"
                                          ofType:@"pem"];
   [GRPCCall useTestCertsPath:certsPath testName:@"foo.test.google.fr" forHost:kLocalSSLHost];
-
-  [super setUp];
 }
 
 - (void)testExceptions {