Feature Request: pass `--cell` flag to VTOrc deployments (required in Vitess v25+)

Feature Description

Vitess v25 makes VTOrc's --cell flag a hard requirement. The change is in https://github.com/vitessio/vitess/pull/20048 — validateCell() previously logged a warning and continued; in v25 it returns a FAILED_PRECONDITION error if --cell is empty. The flag itself was introduced in v24 (https://github.com/vitessio/vitess/pull/19047) to give VTOrc cell/location context for analysis and recovery decisions

The operator's VTOrc deployment does not currently pass --cell. In pkg/operator/vtorc/deployment.go, the flags() function (lines 212-223) sets only:

"topo_implementation":        spec.GlobalLockserver.Implementation,
"topo_global_server_address": spec.GlobalLockserver.Address,
"topo_global_root":           spec.GlobalLockserver.RootPath,
"port":                       planetscalev2.DefaultWebPort,
"clusters_to_watch":          spec.Keyspace + "/" + spec.Shard,
"logtostderr":                true,

Once a cluster upgrades to Vitess v25, every VTOrc managed by this operator will fail to start with a FAILED_PRECONDITION error from validateCell() 😱

What needs to happen

Spec.Cell is already on the vtorc spec (deployment.go:57), and 2 x other components in the operator already pass it to their binaries:

• pkg/operator/vtgate/deployment.go:269 — "cell": spec.Cell.Name
• pkg/operator/vtctld/deployment.go:236 — "cell": spec.Cell.Name

Adding "cell": spec.Cell to vtorc's flags() map matches the existing pattern

Version-skew consideration

--cell was only added to VTOrc in v24, so passing it unconditionally affects users on v23 or older. Worth confirming whether VTOrc on ≤v23 rejects unknown flags or tolerates them before deciding if the flag needs version gating

Impact summary

1. v25+ — VTOrc will not start without this fix
2. v24 — --cell is accepted, missing flag emits a warning
3. ≤v23 — --cell does not exist; behaviour with the flag passed needs verification

Use Case(s)

Every cluster managed by vitess-operator that upgrades to Vitess v25 (GA per the v25.0.0 milestone). Without this change, the operator's VTOrc deployments break on upgrade