Better highlight scheme for force merges

[huydhn]

There are 2 of them atm with dark orange for force merge with failures and light yellow for force merge due to impatience. There are a few more subcategories that we want to capture:

• All failures are marked as flaky, but there are more than 10 of them. So, mergebot refuses to merge normally. This captures CI outages.
• Force merge that ends up in a revert, either the author ignored the signals or Dr.CI made the wrong classification.
• Also need to highlight force merge without trunk jobs as impatient