FIXME(31702) remove fixme, move auxiliaries to the right place and fix hr_lifetime_in_assoc_type warning

src/test/run-pass/issues/auxiliary/issue-31702-2.rs

@@ -16,7 +16,7 @@
 use issue_31702_1::U256;
 
 pub struct Ethash {
-    engine_params: for<'a> fn() -> Option<&'a Vec<u8>>,
+    engine_params: fn() -> Option<&'static Vec<u8>>,
     u256_params: HashMap<String, U256>,
 }
 

src/test/run-pass/issues/issue-31702.rs

@@ -11,11 +11,6 @@
 // run-pass
 // aux-build:issue-31702-1.rs
 // aux-build:issue-31702-2.rs
-// ignore-test: FIXME(#31702) when this test was added it was thought that the
-//                            accompanying llvm update would fix it, but
-//                            unfortunately it appears that was not the case. In
-//                            the interest of not deleting the test, though,
-//                            this is just tagged with ignore-test
 
 // this test is actually entirely in the linked library crates