[TanbirRamim]

In GNU df, -B, -h, -H, -k and -m override each other and the last one on the command line wins. uutils always let -h/-H win, so df -h -B 1K still printed human sizes.

This came up while looking at a Copilot note on #14522 (--total -h --block-size=...).

Checked against GNU df 9.11 (--output=size):

args	GNU 9.11	before	after
-h -B 1K	1K-blocks	Size	1K-blocks
-B 1K -h	Size	Size	Size
-h -k	1K-blocks	Size	1K-blocks
-H -k	1K-blocks	Size	1K-blocks
-k -H	Size	Size	Size
-h -m	1M-blocks	Size	1M-blocks
-m -h	Size	Size	Size

The fix just puts all five options in one overrides_with_all list, so clap keeps the last one. BLOCK_SIZE / DF_BLOCK_SIZE still lose to -h like before (same as GNU).

Added two tests: one for the header in each order, and one that checks -h -B 1 really prints a plain number, not just the right header. Both fail on main.

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