switch web UI images to alpine-slim base

[isegall-da]

cluster test

Pull Request Checklist

Cluster Testing

• If a cluster test is required, comment /cluster_test on this PR to request it, and ping someone with access to the DA-internal system to approve it.
• If an upgrade test is required, comment /upgrade_test on this PR to request it, and ping someone with access to the DA-internal system to approve it.
• If a hard-migration test is required (from the latest release), comment /hdm_test on this PR to request it, and ping someone with access to the DA-internal system to approve it.
• If a logical synchronizer upgrade test is required (from canton-3.5), comment /lsu_test on this PR to request it, and ping someone with access to the DA-internal system to approve it.

PR Guidelines

• Include any change that might be observable by our partners or affect their deployment in the release notes.
• Specify fixed issues with Fixes #n, and mention issues worked on using #n
• Include a screenshot for frontend-related PRs - see README or use your favorite screenshot tool

Merge Guidelines

• Make the git commit message look sensible when squash-merging on GitHub (most likely: just copy your PR description).

[isegall-da]

/cluster_test

[github-actions]

Deploy cluster test triggered for Commit 0cb702804692b969d20c3c17f7702b3fc37d2911 in , please contact a Contributor to approve it in CircleCI: https://app.circleci.com/pipelines/github/DACH-NY/canton-network-internal/69380

[isegall-da]

/cluster_test

[github-actions]

Deploy cluster test triggered for Commit 8b9a23a6c26553df07371108ce96c626c6ab6f17 in , please contact a Contributor to approve it in CircleCI: https://app.circleci.com/pipelines/github/DACH-NY/canton-network-internal/69383

[isegall-da]

/cluster_test

[github-actions]

Deploy cluster test triggered for Commit b8a00afea36b6b10bd7861f3812e54625186189a in , please contact a Contributor to approve it in CircleCI: https://app.circleci.com/pipelines/github/DACH-NY/canton-network-internal/69388

[isegall-da]

/cluster_test

[github-actions]

Deploy cluster test triggered for Commit e46df30c094aa636a8480ef3da936db03ad8db97 in , please contact a Contributor to approve it in CircleCI: https://app.circleci.com/pipelines/github/DACH-NY/canton-network-internal/69390

[isegall-da]

/cluster_test

[github-actions]

Deploy cluster test triggered for Commit f7365b86e56e85490bcbf0696936d229d3d85f36 in , please contact a Contributor to approve it in CircleCI: https://app.circleci.com/pipelines/github/DACH-NY/canton-network-internal/69685

[isegall-da]

/cluster_test

[github-actions]

Deploy cluster test triggered for Commit 48bfd920301e94e2210e875d40f25f40d396b451 in , please contact a Contributor to approve it in CircleCI: https://app.circleci.com/pipelines/github/DACH-NY/canton-network-internal/69725

[isegall-da]

/cluster_test

[github-actions]

Deploy cluster test triggered for Commit 682927d1ef74106422c85ef9387998434a54d2df in , please contact a Contributor to approve it in CircleCI: https://app.circleci.com/pipelines/github/DACH-NY/canton-network-internal/69760