Fewer assertions so that msvc debug build doesn't timeout

tests/ExtraTests/CMakeLists.txt

@@ -564,6 +564,6 @@ add_test(NAME ThreadSafetyTests
 )
 set_tests_properties(ThreadSafetyTests
   PROPERTIES
-    PASS_REGULAR_EXPRESSION "assertions: 8001 | 4000 passed | 4001 failed"
+    PASS_REGULAR_EXPRESSION "assertions: 801 | 400 passed | 401 failed"
     RUN_SERIAL ON
 )

tests/ExtraTests/X94-ThreadSafetyTests.cpp

@@ -28,7 +28,7 @@ TEST_CASE( "Failed REQUIRE in the main thread is fine" ) {
     for ( size_t t = 0; t < 4; ++t) {
         threads.emplace_back( [t]() {
             CAPTURE(t);
-            for (size_t i = 0; i < 1'000; ++i) {
+            for (size_t i = 0; i < 100; ++i) {
                 CAPTURE(i);
                 CHECK( false );
                 CHECK( true );