Remove several methods, deprecated in 1.32

Remove several methods, deprecated in 1.32

I've checked and doubled checked that these methods are no longer used
anywhere in core or extensions, hence removed them. They were hard deprecated
in MediaWiki 1.32.

* OutputPage:
  ** `::showFileCopyError()`
  ** `::showFileRenameError()`
  ** `::showFileDeleteError()`
  ** `::showFileNotFoundError()`

* ApiBase:
  ** `::truncateArray()`

* IcuCollation:
  ** `::getICUVersion()`

* HTMLForm:
  ** `::setSubmitProgressive()`

* ResourceLoaderStartUpModules:
  ** `::getStartupModules()`
  ** `::getLegacyModules()`

* BaseTemplate:
  ** `::msgHtml()`

* QuickTemplate:
  ** `::msgHtml()`

* WatchAction:
  ** `::getUnwatchToken()`

Bug: T220656
Change-Id: Ic1a723a991f4ff63fcb5f045ddcda18d1f8c3c68