build: install essential build tools in teamcity build agents

In #62815, we migrated from an alternative way of installing golang, the
`longsleep/golang-backports` deb repo, to the currently recommended
install method found at https://golang.org/doc/install -- namely, we
download a tarball and then just unzip it in the right spot. This
works perfectly, *except* that the deb package had a dependency on build
tools like `gcc` and `make`, and certain build configurations had come
to depend on their global installation (namely, all those that don't use
`builder.sh` to run a build). This resulted in a couple of failures
being reported:

* https://teamcity.cockroachdb.com/buildConfiguration/Cockroach_ExampleORMs/2834741
* https://teamcity.cockroachdb.com/buildConfiguration/Cockroach_UnitTests_Acceptance/2834732

We just install [`build-essential`](https://packages.ubuntu.com/xenial/build-essential)
here, which is the easiest way to get all of that stuff.

Release note: None

build/packer/teamcity-agent.sh

@@ -31,6 +31,7 @@ apt-get update --yes
 apt-get install --yes sudo
 
 apt-get install --yes \
+  build-essential \
   curl \
   docker-ce \
   docker-compose \