Fix migration-paths job for 11-11

What does this MR do?

Failing job: https://dev.gitlab.org/gitlab/gitlabhq/-/jobs/4976247

$ sed -i "s/gem 'oj', '~> 2.17.4'//" Gemfile
$ bundle update google-protobuf grpc
Fetching gem metadata from https://rubygems.org/......
Fetching gem metadata from https://rubygems.org/.
Resolving dependencies............
Could not find gemnasium-gitlab-service-0.2.6 in any of the sources

gemnasium-gitlab-service was yanked on rubygems.org but it still being used in gitlab 9.3, which lead to this failure

https://gitlab.com/gitlab-org/gitlab-ce/commit/4d7d4a0c16bfcac87416a0ba51296039e4c8b1d4 removed it from gitlab, so I assume that next release(11.5) is the first release I can use for this job.

Does this MR meet the acceptance criteria?

Conformity

• Changelog entry for user-facing changes, or community contribution. Check the link for other scenarios.
• Documentation created/updated or follow-up review issue created
• Code review guidelines
• Merge request performance guidelines
• Style guides
• Database guides
• Separation of EE specific content

Performance and testing

• Review and add/update tests for this feature/bug. Consider all test levels. See the Test Planning Process.
• Tested in all supported browsers

Security

If this MR contains changes to processing or storing of credentials or tokens, authorization and authentication methods and other items described in the security review guidelines:

• Label as security and @ mention @gitlab-com/gl-security/appsec
• The MR includes necessary changes to maintain consistency between UI, API, email, or other methods
• Security reports checked/validated by a reviewer from the AppSec team

Closes #11 (closed)