Avoid panic while panicking because of actix isn't running (#2178)

Some of our tests don't have actix running. @Kouprin found when assert in such tests failed it's not able to see which test fails, only `thread panicked while panicking`. So check actix is running and only shutdown it if so fix this.

Test Plan
---------
```
#[test] 
fn test_assert() {
init_stop_on_panic();
assert(false);
}
```
should give assert fails instead of `thread panicked while panicking`

Cargo.toml

@@ -90,3 +90,6 @@ expensive_tests = []
 regression_tests = []
 old_tests = []
 adversarial = ["near/adversarial", "near-jsonrpc/adversarial"]
+
+[patch.crates-io]
+actix-rt = { git = "https://github.com/actix/actix-net", rev="602db1779eb51d60e0fe5a33d725d1d7fdf540fd" }

core/primitives/src/test_utils.rs

@@ -74,7 +74,9 @@ pub fn init_stop_on_panic() {
         let default_hook = std::panic::take_hook();
         std::panic::set_hook(Box::new(move |info| {
             default_hook(info);
-            actix::System::with_current(|sys| sys.stop_with_code(1));
+            if actix::System::is_set() {
+                actix::System::with_current(|sys| sys.stop_with_code(1));
+            }
         }));
     })
 }