warn: pruning single-issue notices

[MusikAnimal]

Rationales for removal:

{{uw-2redirect}} - pretty sure a bot fixes these
{{uw-articlesig}} - button to add signature was removed from the edit toolbar when editing in mainspace
{{uw-csd}} - better you actually say why the speedy criteria they chose was not applicable
{{uw-directcat}} - surely is a rare occurrance. When it happens, just fix it
{{uw-fuir}} - I believe a bot does this, or those AWB people do. Surely doesn't happen enough to warrant inclusion here
{{uw-imageuse}} - Just going to go ahead and remove this. We have a verbose explanation shown via edit filter when they try to do this. Better we just write a personal note then send them to walls of outdated text
{{uw-incompleteAFD}} - Cyberbot issues more descriptive warnings
{{uw-nonfree}} - this is a warning, not a notice, and should happen when we nominate the image for deletion
{{uw-notaiv}} - we don't ever use this. Just explain the issue to them
{{uw-notifysd}} - this doesn't say what warnings to use
{{uw-notvand}} - tell them which edit was mislabeled
{{uw-patrolled}} - very rare, NPP is supposed to be for experienced editors, and they'll likely be using semi-automated tools that mark the page as patrolled
{{uw-probation}} - talk about being vague. We will be adding a way to issue sanction warnings in the future, otherwise tell them what the situation is
{{uw-refimprove}} - linked resources are grossly outdated, and we usually will instead issue a general notice on adding unverifiable content
{{uw-removevandalism}} - no one uses this
{{uw-repost}} - This is speedy deletion criteria and has it's own template
{{uw-samename}} - renames now happen on meta, and has got to be a pretty rare. The global renamers or stewards should let them know of the issue
{{uw-uaa}} - rarely used, and newcomers don't usually report to UAA
{{uw-upincat}} - a bot removes or "deactivates" these categories, or should
{{uw-uploadfirst}} - same with {{uw-imageuse}}
{{uw-userspacenoindex}} - we draftify user pages like this

[MusikAnimal]

Creating PR for record keeping of the rationale. Boldly going to go ahead and merge

[atlight]

Good work. The list of warnings has barely been touched in 4 or 5 years.

Don't forget to (a) remove {{Twinkle standard installation}} from the template doc pages; and (b) watch WT:TW to let any complainers know that they can use custom warnings.