fix(tests): Correct certificate validation chain for the SKS unit tests #1489

Job	Run time
Debug Build & Unit Tests (gcc)	2m 55s
Debug Build & Unit Tests (gcc, 32bit)	3m 6s
Debug Build & Unit Tests without Subscriptions (gcc)	2m 0s
Debug Build & Unit Tests with Diagnostics (gcc)	2m 51s
Debug Build & Unit Tests with multithreading (gcc)	2m 34s
Debug Build & Unit Tests with Alarms&Conditions (gcc)	10m 59s
Debug Build & Unit Tests (clang)	4m 25s
Debug Build & Unit Tests (tcc)	2m 29s
Encryption (MbedTLS) Build & Unit Tests (gcc)	2m 56s
PubSub Encryption (MbedTLS) Build & Unit Tests (gcc)	3m 3s
PubSub SKS Build & Unit Tests (gcc)	8m 22s
Encryption (OpenSSL) Build & Unit Tests (gcc)	3m 16s
Encryption (LibreSSL) Build & Unit Tests (gcc)	5m 56s
TPM Tool Build	2m 15s
Release Build	1m 31s
Amalgamation Build	55s
Amalgamation Build with Multithreading	57s
Valgrind Build & Unit Tests with MbedTLS (gcc)	12m 51s
Valgrind Build & Unit Tests with OpenSSL (gcc)	12m 55s
Valgrind Examples with MbedTLS (gcc)	58m 19s
Valgrind Examples with OpenSSL (gcc)	58m 33s
Clang Static Analyzer	3m 37s
Build All Companion Specifications	9m 14s
	3h 35m 59s

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