emissary-oci-entrypoint: Remove dependency. (#30967)

Remove the dependency to make it easier to install this along side fips
and non-fips versions.

```
2024/10/16 19:26:57 ERRO failed to test package: unable to build guest: unable to generate image: installing apk packages: error getting package dependencies: solving “emissary-oci-entrypoint” constraint: resolving “emissary-oci-entrypoint-3.9.1-r0.apk” deps:
212
solving “emissary” constraint:   emissary-3.9.1-r0.apk disqualified because emissary-fips-3.9.1-r0.apk already provides cmd:busyambassador
```

Note: this makes the package unusable by itself. I'm not sure if there's
a better way to do this. :(

Related:  chainguard-dev/image-requests#3494

emissary.yaml

@@ -1,7 +1,7 @@
 package:
  name: emissary
  version: 3.9.1
- epoch: 0
+ epoch: 1
  description: "open source Kubernetes-native API gateway for microservices built on the Envoy Proxy"
  copyright:
  - license: Apache-2.0
@@ -138,9 +138,6 @@ subpackages:
 
  - name: ${{package.name}}-oci-entrypoint
  description: Entrypoint for ${{package.name}}
- dependencies:
- runtime:
- - emissary
  pipeline:
  - runs: |
  mkdir -p ${{targets.contextdir}}/usr/bin/