Change testnet automation to use TAR instead of snap (#1809)

ci/testnet-automation.sh

@@ -4,8 +4,8 @@ set -e
 cd "$(dirname "$0")/.."
 
 if [[ -z $USE_PREBUILT_CHANNEL_TARBALL ]]; then
-  echo --- downloading snap from build artifacts
-  buildkite-agent artifact download "solana_*.snap" .
+  echo --- downloading tar from build artifacts
+  buildkite-agent artifact download "solana*.tar.bz2" .
 fi
 
 # shellcheck disable=SC1091
@@ -35,7 +35,7 @@ launchTestnet() {
   if [[ -n $USE_PREBUILT_CHANNEL_TARBALL ]]; then
     net/net.sh start -o noValidatorSanity -t "$CHANNEL"
   else
-    net/net.sh start -o noValidatorSanity -S solana_*.snap
+    net/net.sh start -o noValidatorSanity -T solana*.tar.bz2
   fi
 
   echo --- wait "$ITERATION_WAIT" seconds to complete test