x/pkgsite: replace all internal Googler links

[mvdan]

I see links like TODO(b/139530312), which I assume is an issue link I can't access or at least some text that doesn't make any sense to me.

If we're going to use this issue tracker alone in the future, like other x repos, we should replace all of those with links to issues here. Some TODOs are this way already, such as TODO(golang/go#38513).

Current counts:

$ git log -1 --oneline
7f80893 (HEAD -> master, origin/master, origin/HEAD) internal/database: fix bug with error handling in transact
$ git grep 'TODO(b/' | wc -l
26
$ git grep 'TODO(.*#' | wc -l
8

/cc @julieqiu @jba

[julieqiu]

Thanks for catching! We'll work on fixing these.

[gopherbot]

Change https://golang.org/cl/238319 mentions this issue: internal: clean up issue links

[gopherbot]

Change https://golang.org/cl/238577 mentions this issue: all: clean up issue links

[dmitshur]

There are a few more instances that can be found without the "TODO" prefix:

$ git log -1 --oneline --no-decorate
08e8e66 internal/worker: add /poll and /enqueue endpoints.
$ git grep -E 'b/[0-9]{4}' | wc -l
      12

[gopherbot]

Change https://golang.org/cl/240187 mentions this issue: internal/fetch/dochtml: update package documentation and issue numbers

[dmitshur]

Only 7 more to go after CL 240187.

[gopherbot]

Change https://golang.org/cl/274672 mentions this issue: internal: remove buganizer links

[gopherbot]

Change https://golang.org/cl/274952 mentions this issue: content/static/js: change internal bug refences to external