Pin Docker image versions in compose.yaml files instead of using 'latest'

## Description

Docker appears to download images repeatedly even when no new releases have been conducted, when using the `latest` tag. Consider pinning to dedicated stable versions instead across all compose.yaml files.

## Context

This concern was raised during review of PR #367, which introduces Docker/Podman Compose configurations across multiple integration guides.

## References

- PR: https://github.com/crate/cratedb-guide/pull/367
- Discussion: https://github.com/crate/cratedb-guide/pull/367#discussion_r2407795895
- Requested by: @amotl

## Affected Files

Multiple `compose.yaml` files across the repository, including:
- docs/integrate/influxdb/compose.yaml
- docs/integrate/amqp/compose.yaml
- docs/integrate/collectd/compose.yaml
- docs/integrate/mongodb/compose.yaml
- docs/integrate/mqtt/compose.yaml
- docs/integrate/mysql/compose.yaml
- docs/integrate/oracle/compose.yaml
- docs/integrate/postgresql/compose.yaml
- docs/integrate/statsd/compose.yaml
- docs/integrate/telegraf/compose.yaml
- And others

## Recommendation

Replace `latest` tags with specific version tags (e.g., `crate:5.9.5`, `influxdb:2.7`) to ensure reproducible builds and avoid unnecessary downloads.