gitaly_client: Drop use of squash ID

In the past, the `UserSquash` RPC used to create worktrees in order to
compute the squashed commit. Starting with Gitaly v14.2.0, the RPC was
converted to never create worktrees anymore but instead to always
compute the commit in-memory. The squash ID, which used to indicate to
Gitaly how the worktree should be named and was required such that
`IsSquashInProgress()` knew which worktree to target, is thus not used
at all anymore and callers of `IsSquashInProgress()` have since been
removed.

Drop support for the deprecated squash ID such that it can eventually be
removed from Gitaly's protobuf definitions.

app/models/repository.rb

@@ -1054,10 +1054,10 @@ class Repository
   end
 
   def squash(user, merge_request, message)
-    raw.squash(user, merge_request.id, start_sha: merge_request.diff_start_sha,
-                                       end_sha: merge_request.diff_head_sha,
-                                       author: merge_request.author,
-                                       message: message)
+    raw.squash(user, start_sha: merge_request.diff_start_sha,
+                     end_sha: merge_request.diff_head_sha,
+                     author: merge_request.author,
+                     message: message)
   end
 
   def submodule_links

lib/gitlab/git/repository.rb

@@ -870,9 +870,9 @@ module Gitlab
         end
       end
 
-      def squash(user, squash_id, start_sha:, end_sha:, author:, message:)
+      def squash(user, start_sha:, end_sha:, author:, message:)
         wrapped_gitaly_errors do
-          gitaly_operation_client.user_squash(user, squash_id, start_sha, end_sha, author, message)
+          gitaly_operation_client.user_squash(user, start_sha, end_sha, author, message)
         end
       end
 

lib/gitlab/gitaly_client/operation_service.rb

@@ -259,11 +259,10 @@ module Gitlab
         request_enum.close
       end
 
-      def user_squash(user, squash_id, start_sha, end_sha, author, message, time = Time.now.utc)
+      def user_squash(user, start_sha, end_sha, author, message, time = Time.now.utc)
         request = Gitaly::UserSquashRequest.new(
           repository: @gitaly_repo,
           user: Gitlab::Git::User.from_gitlab(user).to_gitaly,
-          squash_id: squash_id.to_s,
           start_sha: start_sha,
           end_sha: end_sha,
           author: Gitlab::Git::User.from_gitlab(author).to_gitaly,

spec/lib/gitlab/git/repository_spec.rb

@@ -2238,7 +2238,6 @@ RSpec.describe Gitlab::Git::Repository, :seed_helper do
   end
 
   describe '#squash' do
-    let(:squash_id) { '1' }
     let(:branch_name) { 'fix' }
     let(:start_sha) { '4b4918a572fa86f9771e5ba40fbd48e1eb03e2c6' }
     let(:end_sha) { '12d65c8dd2b2676fa3ac47d955accc085a37a9c1' }
@@ -2252,7 +2251,7 @@ RSpec.describe Gitlab::Git::Repository, :seed_helper do
         message: 'Squash commit message'
       }
 
-      repository.squash(user, squash_id, opts)
+      repository.squash(user, opts)
     end
 
     # Should be ported to gitaly-ruby rspec suite https://gitlab.com/gitlab-org/gitaly/issues/1234

spec/lib/gitlab/gitaly_client/operation_service_spec.rb

@@ -308,7 +308,6 @@ RSpec.describe Gitlab::GitalyClient::OperationService do
   end
 
   describe '#user_squash' do
-    let(:squash_id) { '1' }
     let(:start_sha) { 'b83d6e391c22777fca1ed3012fce84f633d7fed0' }
     let(:end_sha) { '54cec5282aa9f21856362fe321c800c236a61615' }
     let(:commit_message) { 'Squash message' }
@@ -321,7 +320,6 @@ RSpec.describe Gitlab::GitalyClient::OperationService do
       Gitaly::UserSquashRequest.new(
         repository: repository.gitaly_repository,
         user: gitaly_user,
-        squash_id: squash_id.to_s,
         start_sha: start_sha,
         end_sha: end_sha,
         author: gitaly_user,
@@ -334,7 +332,7 @@ RSpec.describe Gitlab::GitalyClient::OperationService do
     let(:response) { Gitaly::UserSquashResponse.new(squash_sha: squash_sha) }
 
     subject do
-      client.user_squash(user, squash_id, start_sha, end_sha, user, commit_message, time)
+      client.user_squash(user, start_sha, end_sha, user, commit_message, time)
     end
 
     it 'sends a user_squash message and returns the squash sha' do