change try-runtime endpoints to the new ones (#444)

as part of paritytech/devops#3502, try-runtime
nodes were migrated to a new provider with a new domain address. The PR
fixes all the references to try-runtime nodes on rococo, westend, kusama
and polkadot networks.

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Co-authored-by: fellowship-merge-bot[bot] <151052383+fellowship-merge-bot[bot]@users.noreply.github.com>

.github/workflows/runtimes-matrix.json

@@ -3,14 +3,14 @@
     "name": "polkadot",
     "package": "polkadot-runtime",
     "path": "relay/polkadot",
-    "uri": "wss://polkadot-try-runtime-node.parity-chains.parity.io:443",
+    "uri": "wss://try-runtime.polkadot.io:443",
     "is_relay": true
   },
   {
     "name": "kusama",
     "package": "staging-kusama-runtime",
     "path": "relay/kusama",
-    "uri": "wss://kusama-try-runtime-node.parity-chains.parity.io:443",
+    "uri": "wss://try-runtime-kusama.polkadot.io:443",
     "is_relay": true
   },
   {