remove leftovers of the contracts-rococo parachain (#7638)

There were already previous efforts to remove the contracts-rococo
chain, see #5471, which was done as a response to this comment
#5288 (comment).

This PR intends to fix the parts that were overlooked back then, and
remove all traces of contracts-rococo as it is intended to be replaced
by a new testnet including pallet-revive.

.github/workflows/release-30_publish_release_draft.yml

@@ -54,7 +54,7 @@ jobs:
     needs: [ validate-inputs ]
     uses: "./.github/workflows/release-srtool.yml"
     with:
-       excluded_runtimes: "asset-hub-rococo bridge-hub-rococo contracts-rococo coretime-rococo people-rococo rococo rococo-parachain substrate-test bp cumulus-test kitchensink minimal-template parachain-template penpal polkadot-test seedling shell frame-try sp solochain-template polkadot-sdk-docs-first"
+       excluded_runtimes: "asset-hub-rococo bridge-hub-rococo coretime-rococo people-rococo rococo rococo-parachain substrate-test bp cumulus-test kitchensink minimal-template parachain-template penpal polkadot-test seedling shell frame-try sp solochain-template polkadot-sdk-docs-first"
        build_opts: "--features on-chain-release-build"
        profile: production
     permissions:

.github/workflows/runtimes-matrix.json

@@ -87,17 +87,6 @@
     "uri": "wss://westend-collectives-rpc.polkadot.io:443",
     "is_relay": false
   },
-  {
-    "name": "contracts-rococo",
-    "package": "contracts-rococo-runtime",
-    "path": "cumulus/parachains/runtimes/contracts/contracts-rococo",
-    "header": "cumulus/file_header.txt",
-    "template": "cumulus/templates/xcm-bench-template.hbs",
-    "bench_features": "runtime-benchmarks",
-    "bench_flags": "--genesis-builder-policy=none --exclude-pallets=pallet_xcm",
-    "uri": "wss://rococo-contracts-rpc.polkadot.io:443",
-    "is_relay": false
-  },
   {
     "name": "coretime-rococo",
     "package": "coretime-rococo-runtime",