WARNING for Exim Testsuite:

If you change these certificates you will also need to update the TLSA records in dnszones-src/db.test.ex
and dnszones-src/db.example.com  (the commands are next to each one).
The script "tlsa_regenerate" automates this.

Also, because of the certs changes, the following testcase outputs will change:
2102
5720
5800