test: verify net.box on a schema of version 2.1.3

See #4691 for the problem description. In brief: before the fix net.box
expected _vcollation presence if tarantool's runtime on the server is
new enough disregarding a server's schema version. The old schema
version has no this view, so net.box was unable to connect. After #4691
net.box tolerates lack of the view.

The fix was pushed without a test (see [1]) and now I want to pay this
debt.

[1]: https://lists.tarantool.org/pipermail/tarantool-patches/2020-April/016207.html

Follows up #4307
Follows up #4691
Fixes #5482

NO_DOC=just a new test
NO_CHANGELOG=see NO_DOC