release: backport patrol for 19.2

[tbg]

We don't have a good process around making sure everything that needs to be backported is actually backported. As a stand-in, I'm doing this manually for now. Below is a list of PRs that were not backported into 19.2; please check off any line that has been "acted upon" (i.e. it was decided that no backport is needed, or a backport PR opened). Reminder: we're being very conservative at this point.

Instead of pulling in all of the original authors, I'm asking the TLs to do a pass, which I assume will take care of most items (pretty sure that the majority below won't need backports).

done!

Created via

cat backport.txt  | grep -vE '(✓|◷)$' | grep -vE '(roachtest:)|(sqlsmith:)|(roachprod:)' | cut -c33- | sort | sed -E 's/^/- [ ] /' | pbcopy

where backport.txt was copy-pasted from backboard (pedestrian, I know, but it works fine, and the data isn't readily available as a SQL query, I checked) as of last refresh timestamp 2019-10-16 08:17.