Don't attempt to normalize compiler backtraces

Backtraces can very significantly depending on environment and cause
test suite failures spuriously. Ensuring a proper failure-status should
be sufficient to keep a crash properly documented.

Author: djkoloski

src/test/ui/typeck/issue-103899.rs

@@ -1,9 +1,6 @@
 // check-fail
 // failure-status: 101
-// normalize-stderr-test "note: .*" -> ""
-// normalize-stderr-test "thread 'rustc' .*" -> ""
-// normalize-stderr-test " .*\n" -> ""
-// normalize-stderr-test "  .*\n" -> ""
+// dont-check-compiler-stderr
 // known-bug: #103899
 
 trait BaseWithAssoc {