CP-6649 Rename /etc/modprobe.d/blacklist-bridge to /etc/modprobe.d/blacklist-bridge.conf

Newer versions of udev warn about modprobe.d files without .conf suffix, and future versions may stop loading them entirely
Merge pull request #1584 from alexbrett/CP-6649

CP-6649 Rename /etc/modprobe.d/blacklist-bridge to /etc/modprobe.d/black...