Deprecate container network and host security

Per https://gitlab.com/gitlab-com/Product/-/issues/3600 we are planning to deprecate and remove the Container Network and Host Security categories.

Approvals

Merge requests with changes to stages and groups and significant changes to categories need to be created, approved, and/or merged by each of the below:

• VP of Product @david
• The Product Director relevant to the affected Section(s)
• The Engineering Director relevant to the affected Section(s)
• Director of Product Design @vkarnes

The following people need to be on the merge request so they stay informed:

• Chief Technology Officer @edjdev
• Vice President of Development @clefelhocz1
• Vice President of Quality @meks
• Vice President of User Experience @clenneville
• The Product Marketing Manager relevant to the stage group(s) @cblake
• Senior Manager, Technical Writing @susantacker

After Approvals and Merge

• Create an issue in the triage-ops project to update GitLab Bot automation
• Mention the product group Technical Writer to update the documentation metadata
• Share MR in #product, #development, and relevant #s_, #g_, and #f_ slack channels