Add dictionary for dependency_proxy_manifest_states

What does this MR do and why?

Master is broken because a table was added while we merged the geo dictionary. We did not catch it during the review because we forgot to trigger the pipeline before we merged the MR.

GEO dictionary MR: !104429 (merged)

MR where we added a new table: !102908 (merged)

Rspec error:

Failures:
  1) Database Documentation for each table has a metadata file
     Failure/Error:
       expect(tables_without_metadata).to be_empty, multiline_error(
         'Missing metadata files',
         tables_without_metadata.map { |t| "  #{table_metadata_file(t)}" }
       )
       Missing metadata files:
         ee/db/docs/dependency_proxy_manifest_registry.yml
     # ./ee/spec/lib/ee/gitlab/database/docs/docs_spec.rb:56:in `block (3 levels) in <main>'
     # ./spec/spec_helper.rb:411:in `block (3 levels) in <top (required)>'
     # ./spec/support/sidekiq_middleware.rb:18:in `with_sidekiq_server_middleware'
     # ./spec/spec_helper.rb:403:in `block (2 levels) in <top (required)>'
     # ./spec/spec_helper.rb:399:in `block (3 levels) in <top (required)>'
     # ./lib/gitlab/application_context.rb:59:in `with_raw_context'
     # ./spec/spec_helper.rb:399:in `block (2 levels) in <top (required)>'
     # ./spec/spec_helper.rb:239:in `block (2 levels) in <top (required)>'
     # ./spec/support/system_exit_detected.rb:7:in `block (2 levels) in <main>'
     # ./spec/support/flaky_tests.rb:27:in `block (2 levels) in <main>'
     # ./spec/support/database/prevent_cross_joins.rb:106:in `block (3 levels) in <main>'
     # ./spec/support/database/prevent_cross_joins.rb:60:in `with_cross_joins_prevented'
     # ./spec/support/database/prevent_cross_joins.rb:106:in `block (2 levels) in <main>'
Finished in 7.36 seconds (files took 33.93 seconds to load)
3 examples, 1 failure
Failed examples:
rspec ./ee/spec/lib/ee/gitlab/database/docs/docs_spec.rb:55 # Database Documentation for each table has a metadata file

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