Move the printing of recordings directly to testing/requestErrors

[mkondratek]

The diff information is important to the clients too. Instead of reimplementing it in each client (for the integration test purposes) let's print it directly from the requestErros.

Test plan

• Green CI
• The recording missmatch is clearly reported in the client (test it with https://github.com/sourcegraph/jetbrains/pull/1930)