Remove the deprecated Preprocessor_DOM class, which was hard-deprecated
in 1.34. This begins to simplify parser configuration and reduce redundant
code paths, but I've left two things for cleanup in a future patch:
1. The `preprocessorClass` configuration option to the parser, exposed
in `$wgParserConf`, ServiceWiring, ParserFactory, etc. There is no reason
for this to be exposed as configurable, but I've left this clean up to a
future patch.
2. The `$wgMaxGeneratedPPNodeCount` configuration, exposed also in
ParserOptions. Only Preprocessor_DOM calculated this count, and since
we are only using Preprocessor_Hash now, this configuration has no effect.
But since this value was exposed in ParserOptions and elsewhere, I've
deprecated where needed but left this clean up to a future patch.
Bug: T204945
Change-Id: I727f003f9a42d0c92bcbcce8a8289d5af6cd1298
5cbb64f56a