chore: bump gitlab-zoekt to v1.8.2 on 18-9-stable

What does this MR do and why?

Bumps GITLAB_ZOEKT_SHA and GITLAB_ZOEKT_TAG from v1.8.0 to v1.8.2 on 18-9-stable to build the cng/gitlab-zoekt:v1.8.2 image.

v1.8.2 is a backport of gitlab-org/gitlab-zoekt-indexer!852 which fixes a bug where the Zoekt indexer incorrectly performs an incremental index after a force push, resulting in stale or missing search results for self-managed customers on GitLab 18.9.

• Original issue: gitlab-org/gitlab#593947 (closed)
• Original MR: gitlab-org/gitlab-zoekt-indexer!852 (merged)

Backport chain for 18.9 (SM)

1. ✅ gitlab-zoekt-indexer — cherry-picked fix onto v1.8.0, tagged v1.8.2
2. ⭐ gitlab-org/build/CNG — this MR, builds cng/gitlab-zoekt:v1.8.2 on 18-9-stable
3. ⏳ gitlab-org/gitlab — MR on 18-9-stable-ee bumping GITLAB_ZOEKT_VERSION to 1.8.2
4. ⏳ cloud-native/charts/gitlab-zoekt — MR on main bumping chart to 3.8.4 with image v1.8.2
5. ⏳ gitlab-org/charts/gitlab — MR on 9-9-stable bumping gitlab-zoekt to 3.8.4

Related

• Original fix: gitlab-org/gitlab-zoekt-indexer!852 (merged)
• Fixes: gitlab-org/gitlab#593947 (closed)