Decouple conversion webhook registration from leader election

[sergenyalcin]

Description of your changes

Applies the upjet template fix for the conversion webhook / leader election bug (upjet#) to this provider.

• hack/main.go.tmpl: removes StartWebhooks from both opts structs; adds an explicit startWebhooks block before the canSafeStart gate that calls SetupWebhookWithManager_<group> for both cluster-scoped and namespaced controllers. A comment at the call site explains why webhook registration must happen here rather than inside the gate.

• config/templates/controller.go.tmpl: mirrors the upjet template change — adds SetupWebhookWithManager, removes the if o.StartWebhooks { ... } block from Setup.

• Generated files: all zz_main.go, zz_controller.go, and zz_*_setup.go files regenerated from the updated templates.

Note: This PR uses the forked upjet dependency until the upjet PR is merged.

I have:

• Read and followed Crossplane's contribution process.
• Run make generate and committed the results (ideally in a separate commit).
• Not made any manual changes to generated files, and verified this with make check-diff.

How has this code been tested

https://github.com/crossplane-contrib/provider-upjet-aws/actions/runs/27750948935

[sergenyalcin]

/test-examples="examples/ec2/cluster/v1beta1/vpc.yaml"

[ulucinar]

Thank you @sergenyalcin for working debugging & fixing this issue.