calico: add pod2daemon-flexvol-compat

[imjasonh]

The upstream calico/pod2daemon-flexvol image has these:

crane export calico/pod2daemon-flexvol - | tar -tvf - | grep flexvol              
-rwxr-xr-x  0 0      0     4987070 Nov 22  2021 usr/local/bin/flexvol
-rwxrwxr-x  0 0      0        1703 Nov  9  2021 usr/local/bin/flexvol.sh

And ours has these:

crane export cgr.dev/chainguard/calico-pod2daemon - | tar -tvf - | grep flexvol
-rwxr-xr-x  0 root    root  3870720 Dec 31  1969 usr/bin/calico-pod2daemon-flexvol
-rwxr-xr-x  0 root    root     1703 Dec 31  1969 usr/bin/flexvol.sh

The Tigera operator (and maybe Calico itself) seems to expect the former.