Bump github.com/gravitational/go-mysql to v1.9.1-teleport.4

[rosstimothy]

Closes #53050.

GODEBUG='inittrace=1' ./build/teleport version 2>&1 | rg '^init' | awk '{print $5 " ms " $2}' | sort -n -r | head -10
1.2 ms github.com/aws/aws-sdk-go/aws/endpoints
1.1 ms cloud.google.com/go/compute/apiv1/computepb
1.0 ms k8s.io/client-go/kubernetes/scheme
1.0 ms github.com/microsoft/go-mssqldb/internal/cp
0.97 ms github.com/gravitational/teleport/lib/kube/proxy
0.83 ms github.com/gravitational/teleport/lib/kube/proxy/testing/kube_server
0.74 ms sigs.k8s.io/controller-runtime/pkg/client/apiutil
0.66 ms k8s.io/kubectl/pkg/scheme
0.66 ms github.com/asaskevich/govalidator
0.63 ms go.etcd.io/etcd/api/v3/etcdserverpb

Changelog: Reduce resource consumption and improve latency of tsh ssh.

[backport-bot-workflows]

@rosstimothy See the table below for backport results.

Branch	Result
branch/v17	Failed