KTOR-7482 Use default JDK for running tests on CI

[osipxd]

Subsystem
Tests infrastructure

Motivation
As part of KTOR-7482, we need to run tests against different JDK versions.

Solution
Use the JDK from JAVA_HOME to run tests on CI.

[bjhham]

There seems to be some problems in the TLS package - we got an out-dated ECDH curve java.security.ProviderException: Curve not supported: secp128r1 (1.3.132.0.28) and some rogue reflection java.lang.reflect.InaccessibleObjectException: Unable to make private static java.time.Instant java.time.Instant.create(long,int) accessible: module java.base does not "opens java.time" to unnamed module @5b8bc155

You also seem to have unlocked a consistent failure in testHeaderIsTooLong(), so that's good 😄

[osipxd]

Yes, finally these builds against different Java versions found something :)