Migrate from interop pods to source_files header access (#5760)

FirebaseDatabase.podspec

@@ -25,15 +25,17 @@ Simplify your iOS development, grow your user base, and monetize more effectivel
   s.prefix_header_file = false
 
   base_dir = "Firebase/Database/"
-  s.source_files = base_dir + '**/*.[mh]',
+  s.source_files = [
+    base_dir + '**/*.[mh]',
     base_dir + 'third_party/Wrap-leveldb/APLevelDB.mm',
-    base_dir + 'third_party/SocketRocket/fbase64.c'
+    base_dir + 'third_party/SocketRocket/fbase64.c',
+    'Interop/Auth/Public/*.h',
+    'FirebaseCore/Sources/Private/*.h',
+  ]
   s.public_header_files = base_dir + 'Public/*.h'
-  s.preserve_paths = 'FirebaseCore/Sources/Private/*.h'
   s.libraries = ['c++', 'icucore']
   s.frameworks = 'CFNetwork', 'Security', 'SystemConfiguration'
   s.dependency 'leveldb-library', '~> 1.22'
-  s.dependency 'FirebaseAuthInterop', '~> 1.0'
   s.dependency 'FirebaseCore', '~> 6.8'
   s.pod_target_xcconfig = {
     'GCC_C_LANGUAGE_STANDARD' => 'c99',