Correct delay time for git_sync_pipeline_finished

What does this MR do and why?

Describe in detail what your merge request does and why.

This MR is split from !3589, so we can merge this MR before the next patch release pipeline is created, to avoid the same issue with sync pipeline. For more information, check gitlab-com/gl-infra/delivery#20576.

Content

• Correct delay time for git_sync_pipeline_finished

Previous values:

• multiplier = 1.05
• try = 7

So, the total waiting time for one sync is:

Only 244s, nowhere near our expectation of 15min, or 900s.

So this MR corrects the calculation, so I need to change multiplier and try to 1.4 and 8 respectively. With this, the total waiting time for one sync is slightly higher ~ 17min

Ref: gitlab-com/gl-infra/delivery#20576