repos: don't test x/talks on build dashboard
repos: don't test x/talks on build dashboard

The x/talks repository followed suit after x/blog and x/tour
and has been merged into x/website. CL 366177 removes all of
its moved content, leaving just a README.

Stop displaying it on the build dashboard and running post-submit
tests. Keep TryBots enabled in case a CL is sent with new Go code.

Change-Id: I8c13945b5ae04560d254ba679bf80696f44bed25
Reviewed-on: https://go-review.googlesource.com/c/build/+/366574
Trust: Dmitri Shuralyov <d181b7fea0ec87c86ba5a890ab716db52498e3ba@golang.org>
Run-TryBot: Dmitri Shuralyov <d181b7fea0ec87c86ba5a890ab716db52498e3ba@golang.org>
TryBot-Result: Go Bot <66cb808b70d30c07676d5e946fee83fd561249e5@golang.org>
Reviewed-by: Alexander Rakoczy <60c6d277a8bd81de7fdde19201bf9c58a3df08f4@golang.org>

golang/build,golang/build,golang/build,golang/build