Remove support for MINIFY_HTML

This setting has been causing some problems (see #22188) so I think
we should just remove it.

My understanding is that most users of emscripten use it to generate
JS and not html.  Going forward I'm tempted to also remove the
`--shell-file` command line flag since I'm not sure there any many
compelling use cases for a custom shell html.  While html generation
is certainly useful for quick testing and examples, its not really
something web sites are likely to use in production since they will
likely have their own existing flow for build html.

Fixes: #22188

Author: sbc100

ChangeLog.md

@@ -20,6 +20,9 @@ See docs/process.md for more on how version tagging works.
 
 3.1.65 (in development)
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+- The `MINIFY_HTML` settings, along with the internal use of terser to minify
+  html output was removed.  Folks who want to run terser of their html can
+  continue to do so via an explict separate build step. (#22297)
 
 3.1.64 - 07/22/24
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