Fix Gitaly duration timings for conflict and search RPCs

For many Gitaly RPCs, previously the `gitaly_duration_s` log timings
only accounted for the initial request/response time. We now measure the
total time it takes to consume the streaming response for the following
RPCs:

1. ListConflictFiles
2. SearchFilesByContent

Part of https://gitlab.com/gitlab-org/gitlab/-/issues/30334

changelogs/unreleased/sh-fix-gitaly-conflicts-service-duration.yml

+---
+title: Fix Gitaly duration timings for conflicts and search RPCs
+merge_request: 34909
+author:
+type: other

lib/gitlab/gitaly_client/conflicts_service.rb

@@ -20,9 +20,9 @@ module Gitlab
           our_commit_oid: @our_commit_oid,
           their_commit_oid: @their_commit_oid
         )
-        response = GitalyClient.call(@repository.storage, :conflicts_service, :list_conflict_files, request, timeout: GitalyClient.long_timeout)
-
-        GitalyClient::ConflictFilesStitcher.new(response, @gitaly_repo)
+        GitalyClient.streaming_call(@repository.storage, :conflicts_service, :list_conflict_files, request, timeout: GitalyClient.long_timeout) do |response|
+          GitalyClient::ConflictFilesStitcher.new(response, @gitaly_repo)
+        end
       end
 
       def conflicts?

lib/gitlab/gitaly_client/repository_service.rb

@@ -334,9 +334,9 @@ module Gitlab
 
       def search_files_by_content(ref, query, options = {})
         request = Gitaly::SearchFilesByContentRequest.new(repository: @gitaly_repo, ref: ref, query: query)
-        response = GitalyClient.call(@storage, :repository_service, :search_files_by_content, request, timeout: GitalyClient.default_timeout)
-
-        search_results_from_response(response, options)
+        GitalyClient.streaming_call(@storage, :repository_service, :search_files_by_content, request, timeout: GitalyClient.default_timeout) do |response|
+          search_results_from_response(response, options)
+        end
       end
 
       def disconnect_alternates
@@ -403,14 +403,18 @@ module Gitlab
 
       def gitaly_fetch_stream_to_file(save_path, rpc_name, request_class, timeout)
         request = request_class.new(repository: @gitaly_repo)
-        response = GitalyClient.call(
+        GitalyClient.streaming_call(
           @storage,
           :repository_service,
           rpc_name,
           request,
           timeout: timeout
-        )
+        ) do |response|
+          write_stream_to_file(response, save_path)
+        end
+      end
 
+      def write_stream_to_file(response, save_path)
         File.open(save_path, 'wb') do |f|
           response.each do |message|
             f.write(message.data)