ci: add -j option to autotest for parallel execution

[yutaro-sakamoto]

概要

• CIワークフロー（test-other.yml, coverage.yml）のautotestベースのテストスクリプトに -j オプションを追加し、テストを並列実行するようにした
• file-lock, file-lock2, cobj-idx は並列実行時に競合が発生するため除外
  • この問題はのちにIssueにする

ベンチマーク（テストステップの実行時間）

• 変更前: https://github.com/opensourcecobol/opensourcecobol4j/actions/runs/23829552948
• 変更後: https://github.com/yutaro-sakamoto/opensourcecobol4j/actions/runs/24137687244

テスト	変更前 (秒)	変更後 (秒)	変化
syntax	13	10	-23%
data-rep	22	16	-27%
command-line-options	60	52	-13%
misc	66	51	-23%
i18n_sjis	78	62	-21%
jp-compat	85	68	-20%
run	239	209	-13%

対象テストの実行時間が平均約20%短縮された。

[Copilot]

Pull request overview

This PR updates CI workflows to run GNU Autotest-based test scripts in parallel by adding the -j flag, while keeping the file-lock and file-lock2 suites serialized due to their inter-process locking behavior.

Changes:

• Add conditional -j invocation for most autotest suites in .github/workflows/test-other.yml.
• Add conditional -j invocation for most autotest suites in .github/workflows/coverage.yml, keeping lock-related suites non-parallel.

Reviewed changes

Copilot reviewed 2 out of 2 changed files in this pull request and generated 3 comments.

File	Description
.github/workflows/test-other.yml	Runs a single selected autotest suite with -j except for file-lock suites.
.github/workflows/coverage.yml	Runs the “other tests” list with -j except for file-lock suites to speed up coverage runs.

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