Testing opening a transaction when the DB is deleted crashes in spectacular fashion in 2.0

[alexjpwalker]

The affected test is Scenario: delete a database causes open sessions to fail in database.feature.

In Grakn 1.8, attempting to open a transaction throws an exception if the DB is deleted.

In Grakn 2.0, it fails spectacularly, crashing and killing the entire JVM with a segfault:

#
# A fatal error has been detected by the Java Runtime Environment:
#
#  SIGSEGV (0xb) at pc=0x0000000000000000, pid=99594, tid=0x0000000000001003
#
# JRE version: OpenJDK Runtime Environment (8.0_252-b09) (build 1.8.0_252-b09)
# Java VM: OpenJDK 64-Bit Server VM (25.252-b09 mixed mode bsd-amd64 compressed oops)
# Problematic frame:
# C  0x0000000000000000
#
# Failed to write core dump. Core dumps have been disabled. To enable core dumping, try "ulimit -c unlimited" before starting Java again
#
# An error report file with more information is saved as:
# /private/var/tmp/_bazel_aw/5782084d1ce012ddde90f3bc6bd3ed03/execroot/graknlabs_grakn_core/bazel-out/darwin-fastbuild/bin/test/behaviour/connection/database/test.runfiles/graknlabs_grakn_core/hs_err_pid99594.log
#
# If you would like to submit a bug report, please visit:
#   http://bugreport.java.com/bugreport/crash.jsp
# The crash happened outside the Java Virtual Machine in native code.
# See problematic frame for where to report the bug.
#

The issue appears to be caused by RocksDB cleaning up and removing objects from memory when the DB is deleted, and then attempting to access invalid memory when opening a tx.

We should either fix the test (which seems unlikely) or delete it.

[alexjpwalker]

The test scenario is still named delete a database causes open sessions to fail, and it is still @ignored.