Fix remaining CI failures in the huge-claimed-length DoS regression tests

- Apply the same google-readability-casting fix (std::size_t{N} instead
  of std::size_t(N)) to the "arrays of various sizes" section in
  unit-msgpack.cpp, unit-ubjson.cpp, and unit-bjdata.cpp; only
  unit-cbor.cpp had been fixed previously, since clang-tidy's build
  didn't get far enough to report the other three in the same pass.

- json_sax_dom_parser::start_array()'s max_size() check calls JSON_THROW
  directly rather than going through sax->parse_error(), so unlike the
  scanner's own "not enough data" parse_error it is not gated by
  allow_exceptions=false. On a platform where a header's claimed count
  exceeds max_size() (e.g. 32-bit, for UBJSON/BJData's 0x7FFFFFFF test
  value), from_ubjson/from_bjdata(input, true, false) can therefore still
  throw instead of returning a discarded value. Make that assertion
  tolerant of either outcome, same as the main exception-catching check
  above it.

- Guard all four "a huge claimed length..." SECTIONs with
  #if !defined(JSON_NOEXCEPTION), matching this test suite's existing
  convention for exception-dependent tests: under JSON_NOEXCEPTION,
  JSON_THROW never produces a catchable C++ exception at all (it aborts
  the process), so a section that relies on try/catch to distinguish
  between two acceptable outcomes cannot be expressed under that build
  configuration regardless of platform.

Signed-off-by: Niels Lohmann <mail@nlohmann.me>

tests/src/unit-msgpack.cpp

@@ -1599,6 +1599,11 @@ TEST_CASE("MessagePack")
 
 TEST_CASE("issue #5405 - array reserve for definite-length MessagePack arrays")
 {
+#if !defined(JSON_NOEXCEPTION)
+    // this SECTION relies on catching a thrown exception to distinguish
+    // which of two acceptable, bounded rejections a hostile header took;
+    // under JSON_NOEXCEPTION, JSON_THROW never produces a catchable C++
+    // exception (it aborts instead), so this cannot be tested that way here
     SECTION("a huge claimed length with no element data must not over-allocate")
     {
         // 0xdd: array 32 (four-byte length); claims 0xFFFFFFFF (4294967295)
@@ -1638,14 +1643,15 @@ TEST_CASE("issue #5405 - array reserve for definite-length MessagePack arrays")
         CHECK(threw);
         CHECK(json::from_msgpack(input, true, false).is_discarded());
     }
+#endif
 
     SECTION("arrays of various sizes decode to the same value as before the reserve optimization")
     {
         for (const auto size :
                 {
-                    std::size_t(0), std::size_t(1), std::size_t(5), // small
-                    std::size_t(16384),                             // exactly at the reserve cap
-                    std::size_t(20000)                              // above the reserve cap
+                    std::size_t{0}, std::size_t{1}, std::size_t{5}, // small
+                    std::size_t{16384},                             // exactly at the reserve cap
+                    std::size_t{20000}                              // above the reserve cap
                 })
         {
             CAPTURE(size)