clang-tidy: Temporarily disable readability-function-congnitive-compl…

…exity

...until our CI setup supports overriding configurations on a per-folder
basis (this check generates too many false positives for our unit tests).

.clang-tidy

@@ -36,6 +36,7 @@ Checks: -*,
   performance-*,
   readability-*,
   -readability-avoid-const-params-in-decls,
+  -readability-function-cognitive-complexity,
   -readability-identifier-length,
   -readability-magic-numbers,
   -readability-uppercase-literal-suffix,