fix(dashboards): gitalyctl error count
What
Update the error filter to only filter by level=error
Why
During string match results into false positives, for example when the
name of the project has error
in it for example
gitlab.com/sxuereb/error-debug
would end up matching, and we don't
want that.
Reference: https://gitlab.com/gitlab-com/gl-infra/reliability/-/issues/24000