Add patch to remove block.* settings from LVM and Ceph RBD block volumes

[roosterfish]

This adds a patch to remove the block.* settings from VMs and custom volumes of type block in the LVM and Ceph driver.

That is required after #12805 and follows the same procedure as in #12390.

[roosterfish]

I have removed https://github.com/canonical/lxd/pull/12390/files#diff-967760ebb0c0b53b1eb0f2c1f141563885405f50c26d77dab588b90d26528b0aR1087 in order to be able to patch Ceph RBD backed volumes.
I guess the patch is running locally on each node so this would try to apply the patch on matching Ceph volumes x times (if clustered). Will this cause any race?

[tomponline]

I have removed https://github.com/canonical/lxd/pull/12390/files#diff-967760ebb0c0b53b1eb0f2c1f141563885405f50c26d77dab588b90d26528b0aR1087 in order to be able to patch Ceph RBD backed volumes. I guess the patch is running locally on each node so this would try to apply the patch on matching Ceph volumes x times (if clustered). Will this cause any race?

Yes it will. For Ceph I suggest we need to detect if the member is leader and only run it on the leader.

[roosterfish]

@tomponline looks to be ok now, the code for checking the leader was just a few lines above :)