Disable the new exception handling by default again (#99067)

The new EH was enabled by default right before we've snapped for preview
2, but the various nightly CI tests that were executed after has
uncovered a couple of issues that I've never seen before. I've fixed two
of them, but another one has surfaced today, this time a GC hole that
seems to be related to the new EH. Since there is no time left for
inverstigating and fixing that for preview 2, I am disabling it by
default again.

Co-authored-by: Jan Vorlicek <[email protected]>

src/coreclr/inc/clrconfigvalues.h

@@ -259,7 +259,7 @@ RETAIL_CONFIG_DWORD_INFO(UNSUPPORTED_legacyCorruptedStateExceptionsPolicy, W("le
 CONFIG_DWORD_INFO(INTERNAL_SuppressLostExceptionTypeAssert, W("SuppressLostExceptionTypeAssert"), 0, "")
 RETAIL_CONFIG_DWORD_INFO(INTERNAL_UseEntryPointFilter, W("UseEntryPointFilter"), 0, "")
 RETAIL_CONFIG_DWORD_INFO(INTERNAL_Corhost_Swallow_Uncaught_Exceptions, W("Corhost_Swallow_Uncaught_Exceptions"), 0, "")
-RETAIL_CONFIG_DWORD_INFO(EXTERNAL_LegacyExceptionHandling, W("LegacyExceptionHandling"), 0, "Enable legacy exception handling.");
+RETAIL_CONFIG_DWORD_INFO(EXTERNAL_LegacyExceptionHandling, W("LegacyExceptionHandling"), 1, "Enable legacy exception handling.");
 
 
 ///