feat(docker-compose): add FIPS environment variable to docker-compose for busted tests

[Water-Melon]

KAG-5187

The sibling EE PR: https://github.com/Kong/kong-ee/pull/10031

[Tieske]

Let's keep this as draft until https://github.com/Kong/kong-ee/pull/10031 is green and approved.

[Water-Melon]

@Tieske all the PRs have been approved and are green.

[Tieske]

@Water-Melon thx! looking good.

I added a "do not merge" label, to ensure we do this in the proper order. My suggestion would be this:

• merge the Kong EE PR (https://github.com/Kong/kong-ee/pull/10031) which points to this PRs branch; kag5187_add_fips_env. This will ensure that Kong-EE CI won't fail.
• remove the "Do not merge" label from this PR
• merge this PR in Pongo, such that the fix is in Pongo master
• if the branch gets deleted, restore it immediately
• release Pongo. As part of the release instructions, we create another Kong-EE branch that bumps the Pongo version (from this branch kag5187_add_fips_env to the newly released Pongo version)
• after EE pr with Pongo bump is merged, delete kag5187_add_fips_env branch from the Pongo repo.

This approach should ensure that there are no intermediate CI breakages in either Kong-EE nor Pongo.

[fffonion]

@Tieske For step 1, would you help create a pre-release or a tag pointing to this PR to use for kong-ee? Point something to a branch doesn't seem very reliable.

[Tieske]

Pongo release can be tracked here: https://github.com/Kong/kong-ee/pull/10335