Job operations-puppet-bundle-rspec

Runs `bundler exec rspec` on operations/puppet.git. Made experimental
for now, that requires a basic rspec setup which is currently being
worked on https://gerrit.wikimedia.org/r/#/c/178810/

Bug: T78342
Change-Id: I1c21b98dd73bb40ffd7c52e8340e245bf83ceca8