Zoekt: Start using own webserver binary

What does this MR do?

This MR starts to use our own zoekt-webserver binary from https://gitlab.com/gitlab-org/gitlab-zoekt-indexer/-/tree/main/cmd/gitlab-zoekt-webserver instead of the one that's provided by https://github.com/sourcegraph/zoekt. This is the first step for us to add a new gRPC endpoint to the webserver.

After this MR is merged, we'll be fully using Zoekt as a library.

Also, this gives us more control over Go versions for both binaries: indexer and webserver.

Test plan

1. Go to the webserver directory

   cd gitlab-zoekt-webserver

2. Build the image

   docker build . -t gitlab-zoekt-webserver:new_binary

3. Run the image with

   docker run --rm -p 6070 gitlab-zoekt-webserver:new_binary

4. Open the webserver UI via http://localhost:6070 to verify that it's working

Related issues

• gitlab-org/gitlab#500086 (closed)

Checklist

See Definition of done.

For anything in this list which will not be completed, please provide a reason in the MR discussion

Required

• Merge Request Title, and Description are up to date, accurate, and descriptive
• MR targeting the appropriate branch
• MR has a green pipeline on GitLab.com
• When ready for review, MR is labeled "~workflow::ready for review" per the Distribution MR workflow

Expected (please provide an explanation if not completing)

• Test plan indicating conditions for success has been posted and passes
• Documentation created/updated
• Integration tests added to GitLab QA
• The impact any change in container size has should be evaluated
• New dependencies are managed with GitLab forked renovatebot