Remove CATCH_CONFIG_DISABLE_MATCHERS

Now that the recommended distribution and usage method is proper
library, users can just avoid including the matcher headers to get
basically the same effect.

tests/SelfTest/UsageTests/Compilation.tests.cpp

@@ -79,9 +79,7 @@ namespace { namespace CompilationTests {
         REQUIRE_THROWS(throws_int(true));
         CHECK_THROWS_AS(throws_int(true), int);
         REQUIRE_NOTHROW(throws_int(false));
-#ifndef CATCH_CONFIG_DISABLE_MATCHERS
         REQUIRE_THAT("aaa", Catch::EndsWith("aaa"));
-#endif
         return true;
     }