[CI] Ignore deleted files to do changed files list in content based CI scripts
The filter just lead git diff to ignore any deleted file (D key in the "short diff" display).
Changes triggered by the impossibility to use the format check-apply script locally on the changes from !2222
I am still unsure why we did not have the problem before or why it got triggered in this case, maybe was due to the mix of both moving and deleting some badly formatted files in the same MR
Probably of interest to @e.clerkin as may one day be useful for CI in other repos
If we ever want to play more with this kind of filters latter (ref https://git-scm.com/docs/git-diff#Documentation/git-diff.txt---diff-filterACDMRTUXB):
- Multiple letters can be combined, matching the ones from the "short diff" display (A, C, M, D, ...)
- Upper case letters request the given state/change
- Lower case letters reject/filter-out the given state/change