Update Sidekiq to 2.17.8

Conflicts:
	CHANGELOG
Bump gitlab_git with new rugged

Signed-off-by: Dmitriy Zaporozhets <dmitriy.zaporozhets@gmail.com>
Revert "Update Sidekiq to 2.17.8"

This reverts commit 91ee82c54f41d830922f5504ea37a8a75a0c360b.
Update CHANGELOG for 7.5.3
Merge branch 'release/7.5.3' into '7-5-stable'

Fixes for 7.5.3

See merge request !1302
Version 7.5.3
Merge branch '7-5-stable' into 7-5-zh