Ensure that /var/run/calico exists

[nelljerram]

This is needed when the BIRD image is used independently of calico-node, as it is in the node STs (to model an external node) and the dual ToR STs (to model the ToRs).

Description

A few sentences describing the overall goals of the pull request's commits. Please include

• the type of fix - (e.g. bug fix, new feature, documentation)
• some details on why this PR should be merged
• the details of the testing you've done on it (both manual and automated)
• which components are affected by this PR

Todos

• [ ] Unit tests (full coverage)
• [ ] Integration tests (delete as appropriate) In plan/Not needed/Done
• [ ] Documentation
• [ ] Backport

[nelljerram]

Node ST with this BIRD update is in progress here: https://github.com/projectcalico/node/pull/533