Revert "[clangd][test] Disable a particular testcase in FindExplicitReferencesTest when LLVM_ENABLE_EXPENSIVE_CHECKS"

This reverts commit 42b3c38903.

Should've been fixed by d54d71b67e

clang-tools-extra/clangd/unittests/FindTargetTests.cpp

@@ -770,10 +770,6 @@ TEST_F(FindExplicitReferencesTest, All) {
         "1: targets = {vector}\n"
         "2: targets = {x}\n"},
        // Handle UnresolvedLookupExpr.
-       // FIXME
-       // This case fails when expensive checks are enabled.
-       // Seems like the order of ns1::func and ns2::func isn't defined.
-       #ifndef EXPENSIVE_CHECKS
        {R"cpp(
             namespace ns1 { void func(char*); }
             namespace ns2 { void func(int*); }
@@ -787,7 +783,6 @@ TEST_F(FindExplicitReferencesTest, All) {
         )cpp",
         "0: targets = {ns1::func, ns2::func}\n"
         "1: targets = {t}\n"},
-        #endif
        // Handle UnresolvedMemberExpr.
        {R"cpp(
             struct X {