chore(tests): Switch SPIRE Agent logging configuration back to silence

Signed-off-by: Joonas Bergius <joonas@cosmonic.com>

Author: joonas

tests/fixtures/agent.conf

@@ -1,7 +1,7 @@
 agent {
     data_dir = "$AGENT_DATA_DIR"
-    log_level = "DEBUG"
-    # log_file = "/dev/null"
+    log_level = "ERROR"
+    log_file = "/dev/null"
     trust_domain = "wasmcloud.dev"
     server_address = "$SPIRE_SERVER_HOST"
     server_port = "$SPIRE_SERVER_PORT"