[#55480] Fix Include subprojects return wrong total sum

[Reza98Sh]

What are you trying to accomplish?

Fix bug OP#55480 Project and Include subprojects return wrong total sum values (button 'Include projects')

Ticket

https://community.openproject.org/work_packages/55480

I have changed the numberOfProjectsInFilter$. When this.includeSubprojects is true, it collects all subproject hrefs and updates the number.

Screencast from 2024-08-09 15-48-28.webm

If this method is not considered best practice, please let me know. I am doing my best to improve it.

[Reza98Sh]

@oliverguenther Excuse me, could you please check this and run the workflow? It seems to need approval from a maintainer. Thank you!