25-test_x509.t: test dots in CA file path

25-test_x509.t: test dots in CA file path

Test whether dots in the CA file path breaks the default CA serial
number file path.

Tests for:
  - https://github.com/openssl/openssl/issues/6203
  - https://github.com/openssl/openssl/issues/6489
  - https://github.com/openssl/openssl/pull/6566
  - https://github.com/openssl/openssl/issues/10442

Reviewed-by: Paul Dale <pauli@openssl.org>
Reviewed-by: Tomas Mraz <tomas@openssl.org>
(Merged from https://github.com/openssl/openssl/pull/20873)