gatekeeper update to 3.18.1-bb.0

Package Merge Request

Package Changes

• Synced chart from upstream where all required app.kubernetes.io/* labels existed
• Removed bigbang added label as it is now coming from upstream
• Updated IB image to 3.18.1
• Updated Gluon from 0.5.4 to 0.5.12

Package MR

big-bang/product/packages/policy!301 (merged)

For Issue

Closes big-bang/product/packages/policy#275 (closed)

Upgrade Notices

N/A