Comment out Sentry stacktraces for now

While panic = abort, Sentry collects the same one-line stack trace for all panics,
making it incorrectly dedupe different errors into one.

zebrad/src/sentry.rs

@@ -1,3 +1,4 @@
+#[allow(unused_imports)]
 use sentry::{
     integrations::backtrace::current_stacktrace,
     protocol::{Event, Exception, Mechanism},
@@ -15,7 +16,11 @@ where
             ..Default::default()
         }),
         value: Some(msg.to_string()),
-        stacktrace: current_stacktrace(),
+        // Sentry does not handle panic = abort well yet, and when gibven this
+        // stacktrace, it consists only of this line, making Sentry dedupe
+        // events together by their stacetrace fingerprint incorrectly.
+        //
+        // stacktrace: current_stacktrace(),
         ..Default::default()
     };