Fix exception handling in Gitaly autodetection

In SELinux, the file cannot be written, and `Errno::EACCES`, not
`Errno::ACCESS` is thrown.

Closes https://gitlab.com/gitlab-org/gitlab-ce/issues/65328

changelogs/unreleased/sh-fix-gitaly-access-control.yml

+---
+title: Fix exception handling in Gitaly autodetection
+merge_request: 31285
+author:
+type: fixed

lib/gitlab/gitaly_client.rb

@@ -413,7 +413,7 @@ module Gitlab
       metadata_file = File.read(storage_metadata_file_path(storage))
       metadata_hash = JSON.parse(metadata_file)
       metadata_hash['gitaly_filesystem_id']
-    rescue Errno::ENOENT, Errno::ACCESS, JSON::ParserError
+    rescue Errno::ENOENT, Errno::EACCES, JSON::ParserError
       nil
     end

spec/lib/gitlab/gitaly_client_spec.rb

@@ -17,6 +17,16 @@ describe Gitlab::GitalyClient do
     })
   end
+  describe '.filesystem_id_from_disk' do
+    it 'catches errors' do
+      [Errno::ENOENT, Errno::EACCES, JSON::ParserError].each do |error|
+        allow(File).to receive(:read).with(described_class.storage_metadata_file_path('default')).and_raise(error)
+
+        expect(described_class.filesystem_id_from_disk('default')).to be_nil
+      end
+    end
+  end
+
   describe '.stub_class' do
     it 'returns the gRPC health check stub' do
       expect(described_class.stub_class(:health_check)).to eq(::Grpc::Health::V1::Health::Stub)