Don't use .netrc with SSH

There was a bug that required credentials when using SSH key auth when
using LFS. That bug was fixed so we shouldn't need to add credentials to
.netrc when using SSH anymore.

qa/qa/git/repository.rb

@@ -117,8 +117,6 @@ module QA
         File.binwrite(private_key_file, key.private_key)
         File.chmod(0700, private_key_file)
-        try_add_credentials_to_netrc
-
         @known_hosts_file = Tempfile.new("known_hosts_#{SecureRandom.hex(8)}")
         keyscan_params = ['-H']
         keyscan_params << "-p #{uri.port}" if uri.port
@@ -180,7 +178,6 @@ module QA
       def add_credentials?
         return false if !username || !password
         return true unless ssh_key_set?
-        return true if ssh_key_set? && use_lfs?
         false
       end

qa/spec/git/repository_spec.rb

@@ -115,16 +115,5 @@ describe QA::Git::Repository do
           .to eq("machine foo login user password foo\n")
       end
     end
-
-    describe '#use_ssh_key' do
-      it 'does not add credentials to .netrc' do
-        key = Struct.new(:private_key).new('foo')
-
-        expect(repository).to receive(:try_add_credentials_to_netrc).and_call_original
-        expect(repository).not_to receive(:save_netrc_content)
-
-        repository.use_ssh_key(key)
-      end
-    end
   end
 end