Investigate speeding up hugo command for Handbook workspace

MR: Pending

Description

Following up on conversations here, Handbook repo workspace running hugo command takes around 20 minutes to finish, and we would like to figure out ways for improving this.

Furthermore, currently we configured using 10GB for Handbook repo workspace, as hugo command would event use all those 10GB while processing (after finished, memory usage back to around 5GB). This might worth improving as well.

For reference, for Internal Handbook repo workspace, hugo command takes around 5 minutes to finish. https://gitlab.com/gitlab-com/content-sites/internal-handbook/-/merge_requests/7317#note_2693951626

Acceptance criteria

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• [Describe what must be achieved to complete this issue.]
• [If applicable, please provide design specifications for this feature/enhancement.]
• [If applicable, please list any technical requirements (performance, security, database, etc.)]

Implementation plan

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